ovalbumin and doxantrazole

Intestinal inflammation resulting from manipulation-induced mast cell activation is a crucial mechanism in the pathophysiology of postoperative ileus (POI). Recently it has been shown that spleen tyrosine kinase (Syk) is involved in mast cell degranulation. Therefore, we have evaluated the effect of the Syk-inhibitor GSK compound 143 (GSK143) as potential treatment to shorten POI.. In vivo: in a mouse model of POI, the effect of the Syk inhibitor (GSK143) was evaluated on gastrointestinal transit, muscular inflammation and cytokine production. In vitro: the effect of GSK143 and doxantrazole were evaluated on cultured peritoneal mast cells (PMCs) and bone marrow derived macrophages.. In vivo: intestinal manipulation resulted in a delay in gastrointestinal transit at t=24 h (Geometric Center (GC): 4.4 ± 0.3). Doxantrazole and GSK143 significantly increased gastrointestinal transit (GC doxantrazole (10 mg/kg): 7.2 ± 0.7; GSK143 (1 mg/kg): 7.6 ± 0.6), reduced inflammation and prevented recruitment of immune cells in the intestinal muscularis. In vitro: in PMCs, substance P (0-90 μM) and trinitrophenyl (0-4 μg/ml) induced a concentration-dependent release of β-hexosaminidase. Pretreatment with doxantrazole and GSK143 (0.03-10 μM) concentration dependently blocked substance P and trinitrophenyl induced β-hexosaminidase release. In addition, GSK143 was able to reduce cytokine expression in endotoxin-treated bone marrow derived macrophages in a concentration-dependent manner.. The Syk inhibitor GSK143 reduces macrophage activation and mast cell degranulation in vitro. In addition, it inhibits manipulation-induced intestinal muscular inflammation and restores intestinal transit in mice. These findings suggest that Syk inhibition may be a new tool to shorten POI.

Topics: Aniline Compounds; Animals; Cell Degranulation; Cells, Cultured; Cytokines; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Gastrointestinal Transit; Ileus; Intracellular Signaling Peptides and Proteins; Macrophage Activation; Mast Cells; Mice; Mice, Inbred C57BL; Ovalbumin; Phosphodiesterase Inhibitors; Postoperative Complications; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Pyrimidines; Substance P; Syk Kinase; Thioxanthenes; Xanthones

To study the potential of inflammatory mediators to alter colonic motility, we characterized the response of distal colonic smooth muscle to antigen challenge. Addition of ovalbumin to isolated segments of circular smooth muscle obtained from sensitized guinea pigs produced a biphasic contraction. The initial response consisted of a rapid contraction followed by a late response, which was a more sustained but smaller increase in tone and phasic activity. Interestingly, these two responses could be antagonized differentially. Pretreatment with mepyramine (10 microM) inhibited the initial response, whereas the leukotriene antagonist WY 48252 (10 microM) inhibited the late response. The mast cell stabilizer doxantrazole (0.1 microM) reduced only the late response. Inhibition of cyclooxygenase with meclofenamic acid (1 microM) potentiated both responses, whereas blocking neuronal activity with tetrodotoxin (1 microM) only enhanced the initial response. These data indicate clear differences between the inflammatory mediators important in the initial vs. the late response. The initial response is probably mediated by the release of histamine, with enteric neuronal interactions important in attenuating the magnitude of this response. In contrast, the late response appears to be mediated by the release of peptidyl leukotrienes. In this system, cyclooxygenase products apparently function to decrease the response of the smooth muscle to these mediators. These results suggest that release of mediators during an inflammatory response could profoundly alter colonic motility and that these alterations may be important in the pathophysiological manifestations associated with colonic inflammation.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Antigens; Colon; Guinea Pigs; Histamine; Immunization, Passive; In Vitro Techniques; Male; Muscle Contraction; Muscle, Smooth; Nervous System Physiological Phenomena; Ovalbumin; Prostaglandins; Thioxanthenes; Xanthones

Topics: Animals; Diphenhydramine; DNA; Epithelial Cells; Epithelium; Food Hypersensitivity; Histamine; In Vitro Techniques; Intestinal Absorption; Intestinal Mucosa; Mast Cells; Ovalbumin; Proteins; Rats; Sucrase; Tetrodotoxin; Thioxanthenes; Water-Electrolyte Balance; Xanthones

Investigations into the role of allergic enteropathy in acute and chronic intestinal inflammation have been hampered by the lack of objective confirmation for intestinal mast cell activation. Utilizing an established model of acute allergic enteropathy in the rat, we report the enhanced intraluminal recovery of the mast cell mediator histamine after in vivo antigen challenge in sensitized animals. The enhanced histamine recovery is dose dependent, antigen-specific, and restricted to that segment of bowel challenged, thus confirming local intestinal anaphylaxis. The progression of histologic enteropathy is documented and shown to correlate with the entry of mast cells into the intestinal lumen during, but not before, the anaphylactic response. Pretreatment of the sensitized animal with prostaglandin E2 or doxantrazole, but not cromolyn, significantly inhibits the anaphylactic response.

Topics: Acute Disease; Adjuvants, Immunologic; Anaphylaxis; Animals; Dinoprostone; Enteritis; Female; Histamine; Histamine Release; History, Ancient; Hookworm Infections; Immunization; Nippostrongylus; Ovalbumin; Prostaglandins E; Rats; Rats, Inbred Strains; Thioxanthenes; Xanthones

Peritoneal mast cells from rats immunized with dinitrophenylated ovalbumin (DNP-OA) or normal cells passively sensitized with mouse anti-DNP-OA were incubated in vitro with DNP-bovine serum albumin in the absence of Ca++. This procedure induced desensitization of the cells, such that histamine release was inhibited on subsequent challenge with OA, in the presence of Ca++. The phenomenon of desensitization is supposed to involve early stages in the histamine release process and, thus, two anti-allergic drugs, disodium cromoglycate and doxantrazole, which inhibit an early event(s), were added with the Ca++ -free antigen to investigate whether they had any effect on desensitization. The inhibition of final histamine release caused by each drug and that due to desensitization were approximately additive. It was concluded that the drugs did not influence desensitization of rat mast cells. Thus, their activity was consistent with an effect on an event in the histamine release process, occurring after the generation of the activated stage believed to be responsible for desensitization.

Topics: Animals; Cromolyn Sodium; Dinitrophenols; Female; Histamine Release; Immunoglobulin E; Mast Cells; Mice; Mice, Inbred Strains; Ovalbumin; Rats; Rats, Inbred Strains; Serum Albumin, Bovine; Tachyphylaxis; Thioxanthenes; Xanthones