P-selectin-dependent monocyte recruitment through platelet interaction in intestinal microvessels of LPS-treated mice.
ABSTRACT Although platelets or monocytes are thought to be involved in intestinal inflammation, there has been no report on whether platelets can modulate monocyte recruitment in intestinal microvessels. The objective of this study was to determine whether blockade of platelet adhesion attenuates monocyte recruitment in inflamed murine intestinal microvessels.
Monocytes and platelet-rich plasma were obtained from C57B6/J mice. Interaction of monocytes and platelets with intestinal microvessels was observed under an intravital microscope. Lipopolysaccharide (LPS) was administered intraperitoneally. The effects of anti-P-selectin or anti-platelets antibody treatments or phosphodiesterase (PDE) inhibitors (PDE-3 and PDE-2/4 inhibitor) treatments were also studied.
LPS-treatment increased the rolling and adhesion of both platelets and monocytes. Pretreatment with an anti-P-selectin antibody inhibited the increased platelet adhesion to venular walls and also attenuated the monocyte adhesion. A PDE-2/4 inhibitor (ibuzilast) also ameliorated both platelet and monocyte adhesion. A PDE-3 inhibitor (cilostazol) ameliorated only monocyte adhesion without directly affecting the adhesion of platelets to microvessels.
We observed inhibition of platelets adhesion attenuated monocytes recruitment in intestinal microvessels. Attenuation of LPS induced monocyte adhesion by a specific PDE-3 inhibitor suggests that P-selectin on activated platelets may play an important role through monocyte and platelet interaction.
- Scandinavian Journal of Gastroenterology 10/2012; · 2.33 Impact Factor
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ABSTRACT: Neutrophil migration, one of the major factors predisposing to nonsteroidal anti-inflammatory drugs (NSAIDs)-induced intestinal lesions, consists of several steps, including interaction with P-selectin from platelets. Cilostazol, a specific phosphodiesterase (PDE)-3 inhibitor, suppresses the expression of P-selectin from platelets and reduces interaction between platelets and leukocytes, leading to inflammatory amelioration in several disease models. We tried to clarify the therapeutic effectiveness of cilostazol for NSAID-induced small intestinal lesions. 1) Anti-PSGL-1 antibody (2 mg/kg) or cilostazol (100 mg/kg) was administered to mice one hour before Indomethacin (IND, 2.5 mg/kg) administration for 4 days to evaluate small intestinal lesions. 2) IND-induced migratory behaviors of neutrophils and platelets were evaluated in intestinal vessels by an intravital microscopy. i) IND induced small intestinal lesions with an increase in MPO activity. Anti-PSGL-1 antibody and cilostazol ameliorated intestinal lesions along with suppression of MPO activity. ii) Intravital microscopy revealed that administration of IND increased migration of platelet-bearing neutrophils. Cilostazol treatment ameliorated neutrophil migration by blocking interaction between platelets and neutrophils. Our results suggest that enhanced platelets-bearing neutrophil migration is critically involved in the pathogenesis of IND-induced small intestinal lesions and suggest a potential application of cilostazol for prevention of NSAID-induced small intestinal lesions.Scandinavian Journal of Gastroenterology 09/2012; 8-9(47):993-1002. · 2.33 Impact Factor
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ABSTRACT: The aim of this study was to investigate the effect of interferon (IFN)-α on recruitment of platelets and monocytes within the murine small intestinal venular endothelium. Monocytes were isolated from bone marrow of C57B6 mice. Platelets were collected from murine blood. Rolling and adhesion to submucosal microvessels in the small intestine were examined under an intravital fluorescence microscope after injection of fluorescein-labelled monocytes or platelets. In some mice, IFN-α (5×10(5) U/kg) was administered intraperitoneally. After treatment with an antibody against P-selectin, changes in monocyte and platelet migration were also investigated. Changes in monocyte migration under the condition of thrombocytopenia were also investigated. Platelets and monocytes interacted with murine intestinal microvessels, although only few platelets and monocytes showed migration behaviour. Intraperitoneal injection of IFN-α enhanced the migration of both platelets and monocytes in the intestinal microvessels. Pretreatment with anti-P-selectin attenuated the increase in migration of platelets and monocytes induced by administration of IFN-α. Thrombocytopenia decreased the rolling ratio of monocytes, suggesting that the effect of IFN-α on migration was P-selectin-dependent, derived from both the endothelium of microvessels and platelets. The results of this study suggest that IFN-α acts as a potent proinflammatory agent via its stimulatory effect on the endothelium-platelet-monocyte interaction in intestinal microvessels by a P-selectin-dependent mechanism.Clinical & Experimental Immunology 10/2010; 162(1):156-62. · 3.41 Impact Factor