The effect of ketotifen on nitric oxide synthase activity

Cromoglycate, not ketotifen, ameliorated the injured effect of warm ischemia/reperfusion in rat liver: role of mast cell degranulation, oxidative stress, proinflammatory cytokine, and inducible nitric oxide synthase

Hepatic ischemia/reperfusion (ISCH/REP) is a major clinical problem that is considered to be the most common cause of postoperative liver failure. Recently, mast cells have been proposed to play an important role in the pathophysiology of ISCH/REP in many organs. In contrast, the role played by mast cells during ISCH/REP-induced liver damage has remained an issue of debate. This study aimed to investigate the protective role of mast cells in order to search for an effective therapeutic agent that could protect against fatal ISCH/REP-induced liver damage. A model of warm ISCH/REP was induced in the liver of rats. Four groups of rats were used in this study: Group I: SHAM (normal saline, intravenously [iv]); Group II: ISCH/REP; Group III: sodium cromoglycate + ISCH/REP (CROM + ISCH/REP), and Group IV: ketotifen (KET) + ISCH/REP (KET + ISCH/REP). Liver damage was assessed both histopathologically and biochemically. Mast cell degranulation was assessed histochemically. Lipid peroxidation (malondialdehyde [MDA]) as well as the levels of glutathione (GSH), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α), the formation of nitric oxide (NO), and the expression of inducible NO synthase (iNOS) were determined. The results of this study revealed increased mast cell degranulation in the liver during the acute phase of ISCH/REP. Moreover, CROM, but not KET, decreased the activity of alanine aminotransferase, aspartate aminotransferase, and lactic dehydrogenase and maintained normal liver tissue histology. Both CROM and KET protected against mast cell degranulation in the liver. In addition, both CROM and KET decreased IL-6 and TNF-α. However, CROM, but not KET, decreased MDA formation and increased GSH. Furthermore, KET, but not CROM, increased both NO formation and iNOS expression. In conclusion, this study clearly demonstrated mast cell degranulation in warm ISCH/REP in the liver of rats. More importantly, CROM, but not KET, ameliorated the effect of ISCH/REP-induced injury in rat liver. CROM may protect the liver through mast cell stabilization, inhibition of TNF-α, IL-6, MDA, and iNOS and increased GSH. KET may maintain ISCH/REP-induced liver injury through the NO/iNOS pathway.

Opposite effect of mast cell stabilizers ketotifen and tranilast on the vasoconstrictor response to electrical field stimulation in rat mesenteric artery

OBJECTIVES

We analyzed whether mast cell stabilization by either ketotifen or tranilast could alter either sympathetic or nitrergic innervation function in rat mesenteric arteries.

METHODS

Electrical field stimulation (EFS)-induced contraction was analyzed in mesenteric segments from 6-month-old Wistar rats in three experimental groups: control, 3-hour ketotifen incubated (0.1 αmol/L), and 3-hour tranilast incubated (0.1 mmol/L). To assess the possible participation of nitrergic or sympathetic innervation, EFS contraction was analyzed in the presence of non-selective nitric oxide synthase (NOS) inhibitor L-NAME (0.1 mmol/L), α-adrenergic receptor antagonist phentolamine (0.1 µmol/L), or the neurotoxin 6-hydroxydopamine (6-OHDA, 1.46 mmol/L). Nitric oxide (NO) and superoxide anion (O2.(-) levels were measured, as were vasomotor responses to noradrenaline (NA) and to NO donor DEA-NO, in the presence and absence of 0.1 mmol/L tempol. Phosphorylated neuronal NOS (P-nNOS) expression was also analyzed.

RESULTS

EFS-induced contraction was increased by ketotifen and decreased by tranilast. L-NAME increased the vasoconstrictor response to EFS only in control segments. The vasodilator response to DEA-NO was higher in ketotifen- and tranilast-incubated segments, while tempol increased vasodilator response to DEA-NO only in control segments. Both NO and O2(-) release, and P-nNOS expression were diminished by ketotifen and by tranilast treatment. The decrease in EFS-induced contraction produced by phentolamine was lower in tranilast-incubated segments. NA vasomotor response was decreased only by tranilast. The remnant vasoconstriction observed in control and ketotifen-incubated segments was abolished by 6-OHDA.

CONCLUSION

While both ketotifen and tranilast diminish nitrergic innervation function, only tranilast diminishes sympathetic innnervation function, thus they alter the vasoconstrictor response to EFS in opposing manners.

The role of mast cell stabilization in treatment of postoperative ileus: a pilot study

OBJECTIVES

Although postoperative ileus (POI) is considered multifactorial, intestinal inflammation resulting from manipulation-induced mast cell activation is recognized as an important pathophysiological mechanism. Therefore, mast cell stabilization may represent a new therapeutic approach to shortening POI. The aim of this paper was to study the effect of ketotifen, a mast cell stabilizer, on postoperative gastrointestinal transit in patients who underwent abdominal surgery.

METHODS

In this pilot study, 60 patients undergoing major abdominal surgery for gynecological malignancy with standardized anesthesia were randomized to treatment with ketotifen (4 or 12 mg) or placebo. Patients were treated for 6 days, starting 3 days before surgery. Gastric emptying of liquids, selected as a primary outcome parameter, was measured 24 h after surgery using scintigraphy. Secondary end points were (scintigraphically assessed) colonic transit, represented as geometrical center of activity (segment 1(cecum) to 7(stool)) and clinical parameters.

RESULTS

Gastric retention 1 h after liquid intake was significantly reduced by 12 mg (median 3% (1-7), P=0.01), but not by 4 mg ketotifen (18% (3-45), P=0.6) compared with placebo (16% (5-75)). Twenty-four hour colonic transit in placebo was 0.8 (0.0-1.1) vs. 1.2 (0.2-1.4) colon segments in the 12 mg ketotifen group (P=0.07). Abdominal cramps were significantly relieved in patients treated with 12 mg ketotifen, whereas other clinical parameters were not affected.

CONCLUSIONS

Ketotifen significantly improves gastric emptying after abdominal surgery and warrants further exploration of mast cell stabilizers as putative therapy for POI.

Suppression of plasma matrix metalloproteinase-9 following montelukast treatment in childhood asthma

BACKGROUND

Montelukast and ketotifen are commonly prescribed anti-inflammatory medications used in the treatment of childhood asthma.

METHODS

To investigate the modulation effect of montelukast and ketotifen, the levels of exhaled nitric oxide (eNO) and plasma matrix metalloproteinase-9 (MMP-9) were analyzed in a group of 30 children with mild persistent asthma.

RESULTS

Patients on montelukast therapy for 8 weeks had significantly decreased levels of eNO and plasma MMP-9, which were associated with improved symptoms and enhanced peak expiratory flow but not significantly associated with increased level of tissue inhibitor metalloproteinase-1 (TIMP-1). In contrast, treatment with ketotifen produced no significant changes in these parameters until 4-6 weeks into the therapy and no effect on plasma MMP-9.

CONCLUSION

Leukotriene antagonists, such as montelukast, may be better non-steroidal anti-inflammatory drugs for preventing airway inflammation in mild childhood asthma.

Regulation of stromal cell-derived factor-1 and exhaled nitric oxide in asthmatic children following montelukast and ketotifen treatment

BACKGROUND

Montelukast and ketotifen are oral anti-allergy medications in asthmatic children. This study investigates the modulation effect of montelukast and ketotifen on children with intermittent to mild persistent asthma as demonstrated by the levels of peak expiratory flow (PEF), asthma scores (AS), exhaled nitric oxide (eNO) and plasma stromal cell-derived factor-1 (SDF-1) concentration in a randomized, prospective study.

METHODS

Fifty asthmatic children were enrolled and received 8 weeks of treatment with oral montelukast sodium 5mg chewable tablet administered once daily, or 1mg ketotifen, and were followed for a 4-week post-treatment washout period. ENO concentration, AS and PEF were measured before, 2, 4, 6 and 8 weeks after initial treatment, and 4 weeks after cessation of treatment.

RESULTS

Montelukast therapy was showed to improve AS, PEF and eNO within 2 weeks and remained the improvement during the treatment period. Montelukast also significantly decreased plasma SDF-1 levels after 8 weeks of treatment. In contrast, the ketotifen treatment revealed no significant effects in these clinical parameters until 4 and 6 weeks of the therapy, and did not suppress plasma SDF-1 levels after 8 weeks of treatment. To prove whether montelukast directly suppressed SDF-1 induction, we studied effects of montelukast on the LPS-induced SDF-1 expression and SDF-1-induced chemotaxis of monocytic (THP-1) cells. Montelukast, but not ketotifen, could suppress SDF-1 expression and its related chemotaxis on THP-1 monocytic cells.

CONCLUSIONS

Leukotriene receptor antagonist, such as montelukast, may be a better non-steroid anti-inflammatory drug for mild childhood asthma in preventing airway inflammation.

Ketotifen abrogates local and systemic consequences of rat intestinal ischemia-reperfusion injury

BACKGROUND

Mast cell-derived vasoactive and pro-inflammatory mediators, particularly histamine, might contribute to local tissue damage and multiorgan dysfunction induced by intestinal ischemia/reperfusion (I/R). The purpose of the present study was to evaluate the effects of the mast cell stabilizer, ketotifen, on leukocyte adhesion within, and tissue leakage from the mucosal villous microcirculation after intestinal I/R.

METHODS

Superior mesenteric arteries of untreated and ketotifen-pretreated (1 mg/kg orally twice daily for 3 days, and 90 min prior to ischemia) Piebald-Viral-Glaxo (PVG) rats were clamped for 30 min (n = 12 per group; sham operated controls n = 12). Mucosal surfaces of exteriorized ileal segments were visualized, and leukocyte adherence in, and macromolecular leakage (MML) from individual villi were followed for 2 h after clamp removal using in vivo microscopy. Blood pressure and heart rate were monitored, and lung tissue damage was assessed by histology.

RESULTS

Ten untreated animals subjected to intestinal I/R failed to survive the reperfusion period, leukocyte adhesion (P < 0.001) and MML (P < 0.001) were increased at all time-points and blood flow stasis eventually ensued. In contrast, all ketotifen-pretreated I/R animals survived the duration of the study. Ketotifen abrogated I/R-induced leukocyte adherence within the villus mucosal capillaries and supplying arterioles and largely prevented pulmonary injury, yet surprisingly had no effect on intestinal vascular leakage.

CONCLUSIONS

This is the first study to demonstrate that ketotifen is a powerful inhibitor of I/R-induced leukocyte adhesion and can prevent localized and reduce remote organ damage after intestinal I/R injury. However, its effects are manifested in the absence of any influence on intestinal I/R-induced vascular leakage.

Effects of mast-cell stabilization in cerulein-induced acute pancreatitis in rats

AIM

In this study we aimed to clarify the role of mast cells in the development and progression of inflammation in cerulein-induced acute pancreatitis (AP) in rats. We have also examined the effects of ketotifen; a mast-cell stabilizing agent in the treatment of acute pancreatitis and its relation with nitric oxide (NO) synthesis.

METHODS

In the first part of the study we planned to examine the effects mast cell stabilization in acute pancreatitis, while the second part was focused on examining the relation between NO synthesis and the potential effects of ketotifen in AP. Wistar albino rats were randomly divided into 6 groups (n: 10). In the first part of the study, AP was induced by four subcutaneous (sc) injections of 20 microg/kg body weight of cerulein at hourly intervals in Groups A and B while Group C was treated with saline as the control group. Group B was pretreated with ketotifen 1 mg/kg (ip). In the second part, the study design was similar except for the inhibition of nitric oxide synthesis by N-nitro L-arginine methyl ester (L-NAME) 30 mg/kg (ip) in Groups D, E and F. Group D was treated with L-NAME and cerulein and Group E was treated with ketotifen, L-NAME and cerulein. Group F was treated with L-NAME and saline as the control group. Serum amylase activity and pancreatic myeloperoxidase activity (MPO) were measured. Pancreatic histology and mast-cell count in pancreatic tissue were evaluated.

RESULTS

Mast cell count was found to be increased in the pancreatic tissue in cerulein-induced AP. (2.93+/-0.26 vs 1.98+/-0.26; p<0.001). Ketotifen treatment significantly reduced cerulein induced edema (1.30+/-0.21 vs 0.70+/-0.15; p<0.001), neutrophil infiltration (1.50+/-0.16 vs 0.60+/-0.16; p<0.001) and attenuated the increase in amylase (4394.0+/-149.5 U/L vs 3350.5+/-216.9 U/L; p<0.05) and MPO activity (1.14+/-0.13 U/gr tissue vs 0.54+/-0.08 U/gr tissue; p<0.001). Mast-cell count in pancreatic tissue was also decreased significantly with ketotifen pretreatment (2.93+/-0.26 vs 1.70+/-0.21; p<0.05). Inhibition of NO synthesis with L-NAME treatment decreased the beneficial effects of ketotifen.

CONCLUSION

It seems likely that mast cell activity may play an important role in the initiation and progression of acute pancreatitis. Ketotifen treatment may reduce the severity of AP in rats. The protective action of ketotifen in cerulein-induced acute pancreatitis is most probably owing to mast cell stabilization and stimulation of NO synthesis.

Effects of mast cell membrane stabilizing agents in a rat lung ischemia-reperfusion model

BACKGROUND

The aim of this study was to test the hypothesis that agents which stabilize the mast cell membrane may modulate the phenotype of the vascular wall in a lung ischemia-reperfusion model, including altering expression of endothelial and leukocyte adhesion receptors and the inducible nitric oxide synthase (NOS-2).

METHODS

Three sets of rats were given either intravenous saline (group A), ketotifen (group B), or cromolyn (group C), respectively. The left pulmonary artery was ligated temporarily and reopened after 2 hours of ischemia. Then, after a 2-hour period of reperfusion, the left lung was excised. ICAM-1 and NOS-2 were measured at the protein level by Western blotting, and cGMP levels were measured by enzyme-linked immunosorbent assay in the lung tissue specimens for each drug group.

RESULTS

ICAM-1 expressions, determined as the intensity of a given band on the Western blot, were 197+/-59 in group B and 195+/-83 in group C versus 369+/-114 in group A (p = 0.002 for analysis of variance). In contrast with ICAM-1, NOS-2 expression was increased by ketotifen or cromolyn treatment (464+/-82 in group B and 507+/-93 in group C, compared with 377+/-44 for group A, p = 0.007). The finding of increased NOS-2 expression in groups B and C is consistent with the observed increase in tissue cGMP levels in the same groups (1.92+/-0.9 pmol/mL for group A versus 7.8+/-3.5 pmol/mL for group B, and 12.4+/-5.8 pmol/mL for group C, p = 0.0004).

CONCLUSIONS

These data establish that mast cell stabilizing agents modulate the vascular phenotype in the setting of pulmonary ischemia and reperfusion by decreasing ICAM-1 expression, augmenting expression of NOS-2, and increasing tissue cGMP levels. As decreasing ICAM-1 expression and increasing cGMP levels have proven useful to limit proinflammatory mechanisms of tissue injury, mast cell stabilizing agents may provide a new therapeutic option to improve organ function in the setting of reperfusion.

Membrane stabilization in harvested vein graft storage: effects on adhesion molecule expression and nitric oxide synthesis

OBJECTIVE

Expression of cellular adhesion molecules in human saphenous vein grafts may occur even during harvesting and storage, before the grafts have been implanted as bypass conduits. This may play a role in graft adaptation to arterial flow conditions, which may play an important role in late graft patency. In this study, ketotifen, a mast cell membrane stabilizing agent was studied for its effects on reducing endothelial reactivity during storage of harvested vein graft segments.

METHODS

Human saphenous vein grafts, obtained from seven patients and then divided into two equal parts of control and study specimens, were stored in either heparinized blood (Group A) or heparinized blood containing 100 microg/ml ketotifen (Group B) for 1 h at room temperature. Specimens were analyzed by Western blotting to quantify ICAM-1, E-selectin, P-selectin, VCAM-1, and inducible nitric oxide synthase (NOS-2) expression, as well as tissue cGMP levels in response to topical application of an endothelium-independent vasodilator.

RESULTS

ICAM-1, E-selectin and P-selectin expression did not differ between the groups. However, VCAM-1 expression was significantly lower in Group B (460 +/- 29 vs. 289 +/- 50, P = 0.01). NOS-2 expression (488 +/- 64 vs. 577 +/- 38, P = 0.02) and tissue cGMP levels (2.2 +/- 0.6 pmol/ml vs. 5.7 +/- 1.7 pmol/ml, P = 0.01) in response to nitroglycerin (24 +/- 10% vs. 11 +/- 5%, P = 0.02) were higher in Group B.

CONCLUSIONS

Of all of the adhesion receptors studied, only VCAM-1 expression was reduced by a mast cell membrane-stabilizing agent, perhaps because of activation of the venous endothelium during harvest prior to ketotifen exposure. However, ketotifen also augmented NOS-2 expression, increased tissue cGMP levels in response to nitroglycerin. These actions may improve vascular homeostasis in the venous graft, suggesting the possibility that this strategy may improve long-term graft patency.