title: IL-1β reduces tonic contraction of mesenteric lymphatic muscle cells, with the involvement of cycloxygenase-2 and prostaglandin E2.
abstract: OBJECTIVE
  The lymphatic system maintains tissue homeostasis by unidirectional lymph flow, maintained by tonic and phasic contractions within subunits, 'lymphangions'. Here we have studied the effects of the inflammatory cytokine IL-1β on tonic contraction of rat mesenteric lymphatic muscle cells (RMLMC).
  
  
  METHODS
  We measured IL-1β in colon-conditioned media (CM) from acute (AC-CM, dextran sodium sulfate) and chronic (CC-CM, T-cell transfer) colitis-induced mice and corresponding controls (Con-AC/CC-CM). We examined tonic contractility of RMLMC in response to CM, the cytokines h-IL-1β or h-TNF-α (5, 10, 20 ng·mL(-1) ), with or without COX inhibitors [TFAP (10(-5)  M), diclofenac (0.2 × 10(-5)  M)], PGE2 (10(-5)  M)], IL-1-receptor antagonist, Anakinra (5 μg·mL(-1) ), or a selective prostanoid EP4 receptor antagonist, GW627368X (10(-6) and 10(-7)  M).
  
  
  RESULTS
  Tonic contractility of RMLMC was reduced by AC- and CC-CM compared with corresponding control culture media, Con-AC/CC-CM. IL-1β or TNF-α was not found in Con-AC/CC-CM, but detected in AC- and CC-CM. h-IL-1β concentration-dependently decreased RMLMC contractility, whereas h-TNF-α showed no effect. Anakinra blocked h-IL-1β-induced RMLMC relaxation, and with AC-CM, restored contractility to RMLMC. IL-1β increased COX-2 protein and PGE2 production in RMLMC.. PGE2 induced relaxations in RMLMC, comparable to h-IL-1β. Conversely, COX-2 and EP4 receptor inhibition reversed relaxation induced by IL-1β.
  
  
  CONCLUSIONS
  The IL-1β-induced decrease in RMLMC tonic contraction was COX-2 dependent, and mediated by PGE2 . In experimental colitis, IL-1β and tonic lymphatic contractility were causally related, as this cytokine was critical for the relaxation induced by AC-CM and pharmacological blockade of IL-1β restored tonic contraction.
authors.affiliation: Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center - Shreveport, Shreveport, LA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Al-Kofahi
authors.affiliation: Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center - Shreveport, Shreveport, LA, USA.|Department for General and Visceral Surgery, University Hospital Muenster, Muenster, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Becker
authors.affiliation: Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center - Shreveport, Shreveport, LA, USA.
authors.forename: F N E
authors.initials: FN
authors.lastname: Gavins
authors.affiliation: Department of Microbiology and Immunology, Louisiana State University Health Sciences Center - Shreveport, Shreveport, LA, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Woolard
authors.affiliation: Department of Microbiology and Immunology, Louisiana State University Health Sciences Center - Shreveport, Shreveport, LA, USA.
authors.forename: I
authors.initials: I
authors.lastname: Tsunoda
authors.affiliation: Department of Obstetrics and Gynecology, Louisiana State University Health Sciences Center - Shreveport, Shreveport, LA, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Medicine, Division of Rheumatology, Louisiana State University Health Sciences Center - Shreveport, Shreveport, LA, USA.
authors.forename: D
authors.initials: D
authors.lastname: Ostanin
authors.affiliation: Department of Medicine, Cardiovascular Research Institute, Texas A&M Health Science Center, College Station, TX, USA.
authors.forename: D C
authors.initials: DC
authors.lastname: Zawieja
authors.affiliation: Department of Medicine, Cardiovascular Research Institute, Texas A&M Health Science Center, College Station, TX, USA.
authors.forename: M
authors.initials: M
authors.lastname: Muthuchamy
authors.affiliation: Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: P Y
authors.initials: PY
authors.lastname: von der Weid
authors.affiliation: Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center - Shreveport, Shreveport, LA, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Alexander
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003092:Colitis / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000378:metabolism / Q000502:physiology*; D015232:Dinoprostone / Q000378:metabolism / Q000502:physiology*; D053583:Interleukin-1beta / Q000494:pharmacology*; D008198:Lymph Nodes / Q000166:cytology; D008297:Male; D008643:Mesentery / Q000166:cytology; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D032342:Muscle Cells / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D051546:Cyclooxygenase 2; C489691:Ptgs2 protein, rat; D015232:Dinoprostone