Novel mast cell stabilizers in the treatment of postoperative ileus
SH van Bree1, SA Snoek1, SA van Diest1, L Elbers1, FW Hilbers1, S Duijst1, J van der Vliet1, RM van den Wijngaard1, C
Cailotto1, WJ de Jonge1, GE Boeckxstaens1,5.
1
Tytgat institute of Liver and Intestinal Research, Department of Gastroenterology& Hepatology, Academic Medical Center,
Amsterdam, the Netherlands. 2Department of Gastroenterology, University Hospital Leuven, Catholic University of Leuven,
Leuven, Belgium.
Both animal and human studies indicate an important role for mast cells in the pathogenesis of
postoperative ileus (POI), suggesting mast cell stabilization as a new therapeutic approach to prevent POI.
In the present study, we evaluated the stabilizing effect of two new potential mast cell stabilizers in vitro
and evaluated their ability to prevent POI in mice.
In vitro: Freshly isolated mouse peritoneal cells were cultured for 3 weeks in the presence of 100 ng/ml
stem cell factor, yielding a >94% (FceRI +, CD117 +) pure peritoneal mast cell population. The effect of
the IL-1R antagonist anakinra and the novel spleen tyrosine kinase (SYK) inhibitor GSKcompound#1
(GSK#1) was evaluated on SP induced release of β-hexosaminidase. Release was expressed as % of total
cellular β-hexosaminidase content. In vivo: The effect of anakinra (100 mg/kg i.p.) or GSK#1 (100 mg/kg
orally) was evaluated in a mouse model of POI. Mice were subjected to intestinal manipulation; 24h after
surgery gastrointestinal transit was determined and intestinal inflammation was assessed by the number of
MPO-positive cells in the muscularis externa of the small intestine.
In vitro: Substance P (0-350 uM) induced a dose-dependent release of β-hexosaminidase (max. release by
peritoneal mast cells: 51.5±3.8% of their β-hexosaminidase content). Pretreatment for 30 min with the
mast cell stabilizer doxantrazole (840uM), anakinra (480 uM) or GSK#1 (340 uM) significantly inhibited
substance P (90 uM) induced β-hexosaminidase release (vehicle: 43.3±1.2% release of total content,
doxantrazole: 2.2±0.1%, anakinra: 4.5±0.1%, GSK#1: 18.7±1.0%; mean±SEM, one-way ANOVA). In
vivo: Intestinal manipulation resulted in a reduction of intestinal transit at t=24h (GC 4.7±0.3). Anakinra
significantly increased transit (geometric center: 8.0±1.1, p=0.009) and reduced intestinal muscularis
inflammation (number of neutrophils: anakinra 56±11 vs vehicle 104±11, p=0.008). GSK#1 reduced
neutrophil recruitment (49±6 vs vehicle 113±6, p<0.0001), but had no effect on transit (p=0.773) in a dose
of 100 mg/kg. Our data indicate that the IL-1 receptor antagonist anakinra and the Syk-inhibitor GSK#1
reduce SP-induced mast cell degranulation in isolated peritoneal mast cells and ameliorate manipulation
induced intestinal inflammation. In contrast to GSK#1, anakinra prevented the delay in postoperative
intestinal transit in a mouse model of POI. Additional experiments testing different dosing are ongoing to
further explore the effect of GSK#1 on POI. These findings further underscore the importance of mast
cells in the development of POI and suggest that anakinra and GSK#1 may be new tools to shorten POI.