Induction of colitis causes inflammatory responses in fat depots: evidence for substance P pathways in human mesenteric preadipocytes.
Intracolonic administration of trinitrobenzene sulfonic acid in mice causes inflammation in the colon that is accompanied by increased expression of proinflammatory cytokines and of the substance P (SP), neurokinin 1 receptor (NK-1R) in the proximal mesenteric fat depot. We also investigated whether human mesenteric preadipocytes contain NK-1R and examined the functional consequences of exposure of these cells to SP as it relates to proinflammatory signaling. We found that human mesenteric preadipocytes express NK-1R both at the mRNA and protein levels. Exposure of human mesenteric preadipocytes to SP increased NK-1R mRNA and protein expression by 3-fold, and stimulated IL-8 mRNA expression and protein secretion. This effect was abolished when these cells were pretreated with the specific NK-1R antagonist CJ 012,255. Moreover, human mesenteric preadipocytes transfected with a luciferase promoter/reporter system containing the IL-8 promoter with a mutated NF-kappaB site lost their ability to respond to SP, indicating that SP-induced IL-8 expression is NF-kappaB-dependent. This report indicates that human mesenteric preadipocytes contain functional SP receptors that are linked to proinflammatory pathways, and that SP can directly increase NK-1R expression. We speculate that mesenteric fat depots may participate in intestinal inflammatory responses via SP-NK-1R-related pathways, as well as other systemic responses to the presence of an ongoing inflammation of the colon.
Karagiannides
Iordanes
I
Gastrointestinal Neuropeptide Center, Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
Kokkotou
Efi
E
Tansky
Morris
M
Tchkonia
Tamara
T
Giorgadze
Nino
N
O'Brien
Michael
M
Leeman
Susan E
SE
Kirkland
James L
JL
Pothoulakis
Charalabos
C
D050153:Abdominal Fat / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D002633:Chemotaxis; D003092:Colitis / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology*; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D008643:Mesentery / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics; D018040:Receptors, Neurokinin-1 / Q000378:metabolism; D015398:Signal Transduction; D013373:Substance P / Q000378:metabolism / Q000494:pharmacology*; D013997:Time Factors; D014302:Trinitrobenzenesulfonic Acid / Q000008:administration & dosage / Q000494:pharmacology
D016207:Cytokines; D016328:NF-kappa B; D012333:RNA, Messenger; D018040:Receptors, Neurokinin-1; D013373:Substance P; D014302:Trinitrobenzenesulfonic Acid; D048049:Extracellular Signal-Regulated MAP Kinases