Interleukin-10-independent anti-inflammatory actions of glucagon-like peptide 2.
Glucagon-like peptide 2 (GLP-2) is an important intestinal growth factor with anti-inflammatory activity. We hypothesized that GLP-2 decreases mucosal inflammation and the associated increased epithelial proliferation by downregulation of Th1 cytokines attributable to reprogramming of lamina propria immune regulatory cells via an interleukin-10 (IL-10)-independent pathway. The effects of GLP-2 treatment were studied using the IL-10-deficient (IL-10(-/-)) mouse model of colitis. Wild-type and IL-10(-/-) mice received saline or GLP-2 (50 microg/kg sc) treatment for 5 days. GLP-2 treatment resulted in significant amelioration of animal weight loss and reduced intestinal inflammation as assessed by histopathology and myeloperoxidase levels compared with saline-treated animals. In colitis animals, GLP-2 treatment also reduced crypt cell proliferation and crypt cell apoptosis. Proinflammatory (IL-1beta, TNF-alpha, IFN-gamma,) cytokine protein levels were significantly reduced after GLP-2 treatment, whereas IL-4 was significantly increased and IL-6 production was unchanged. Fluorescence-activated cell sorting analysis of lamina propria cells demonstrated a decrease in the CD4(+) T cell population following GLP-2 treatment in colitic mice and an increase in CD11b(+)/F4/80(+) macrophages but no change in CD25(+)FoxP3 T cells or CD11c(+) dendritic cells. In colitis animals, intracellular cytokine analysis demonstrated that GLP-2 decreased lamina propria macrophage TNF-alpha production but increased IGF-1 production, whereas transforming growth factor-beta was unchanged. GLP-2-mediated reduction of crypt cell proliferation was associated with an increase in intestinal epithelial cell suppressor of cytokine signaling (SOCS)-3 expression and reduced STAT-3 signaling. This study shows that the anti-inflammatory effects of GLP-2 are IL-10 independent and that GLP-2 alters the mucosal response of inflamed intestinal epithelial cells and macrophages. In addition, the suggested mechanism of the reduction in inflammation-induced proliferation is attributable to GLP-2 activation of the SOCS-3 pathway, which antagonizes the IL-6-mediated increase in STAT-3 signaling.
Faculty of Medicine, Gastrointestinal Research Group, Institute of Infection, Immunity and Inflammation, Faculty of Medicine, University of Calgary, Health Sciences Centre, Calgary, Alberta, Canada.
Catherine P A
CP
Ivory
Laurie E
LE
Wallace
Donna-Marie
DM
McCafferty
David L
DL
Sigalet
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D003092:Colitis / Q000188:drug therapy; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D053767:Glucagon-Like Peptide 2 / Q000494:pharmacology*; D016753:Interleukin-10 / Q000172:deficiency / Q000502:physiology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009092:Mucous Membrane / Q000166:cytology / Q000187:drug effects
D000893:Anti-Inflammatory Agents; D016207:Cytokines; D053767:Glucagon-Like Peptide 2; D016753:Interleukin-10