Prostaglandin modulation of airway inflammation and hyperresponsiveness in mice sensitized without adjuvant.
ABSTRACT As adjuvant during sensitization may cause unspecific immune reactions, the aim of the present study was to define the role of cyclooxygenase (COX) activity on airway inflammation and airway hyperresponsiveness (AHR) in an adjuvant-free allergic mouse model. Administration of diclofenac and indomethacin (non-selective COX inhibitors), FR122047 (COX-1 inhibitor) and lumiracoxib (selective COX-2 inhibitor) enhanced AHR. Only diclofenac and lumiracoxib reduced the inflammatory cell content of bronchoalveolar lavage (BAL). Moreover, levels of prostaglandins in BAL were reduced by indomethacin and FR122047 but were unaffected by lumiracoxib. However, compared with antigen controls, none of the COX inhibitors displayed major effects on the production of cytokines, smooth muscle mass, number of goblet cells and eosinophils, or collagen deposition in the airways. These data in mice sensitized without adjuvant support the fact that COX products have a general bronchoprotective role in allergic airway inflammation. Furthermore, the data suggest that COX-1 activity predominantly generates prostanoids in BAL, whereas COX-2 activity is associated with the accumulation of inflammatory cells in BAL. This study further supports that AHR on the one hand, and the inflammatory response and generation of prostanoids on the other, are dissociated and, at least in part, uncoupled events.
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ABSTRACT: To investigate the effect of polydatin (PD), a resveratrol glucoside, on mast cell degranulation and anti-allergic activity. After the rats were orally sensitized with ovalbumin (OVA) for 48 d and underwent PD treatment for 4 d, all the rats were stimulated by 100 mg/mL OVA for 24 h and then sacrificed for the following experiments. The small intestines from all the groups were prepared for morphology examination by hematoxylin and eosin staining. We also used a smooth muscle organ bath to evaluate the motility of the small intestines. The OVA-specific immunoglobulin E (IgE) production and interleukin-4 (IL-4) levels in serum or supernatant of intestinal mucosa homogenates were analyzed by enzyme-linked immunosorbent assay (ELISA). Using toluidine blue stain, the activation and degranulation of isolated rat peritoneal mast cells (RPMCs) were analyzed. Release of histamine from RPMCs was measured by ELISA, and regulation of PD on intracellular Ca(2+) mobilization was investigated by probing intracellular Ca(2+) with fluo-4 fluorescent dye, with the signal recorded and analyzed. We found that intragastric treatment with PD significantly reduced loss of mucosal barrier integrity in the small intestine. However, OVA-sensitization caused significant hyperactivity in the small intestine of allergic rats, which was attenuated by PD administration by 42% (1.26 ± 0.13 g vs OVA 2.18 ± 0.21 g, P < 0.01). PD therapy also inhibited IgE production (3.95 ± 0.53 ng/mL vs OVA 4.53 ± 0.52 ng/mL, P < 0.05) by suppressing the secretion of Th2-type cytokine, IL-4, by 34% (38.58 ± 4.41 pg/mL vs OVA 58.15 ± 6.24 pg/mL, P < 0.01). The ratio of degranulated mast cells, as indicated by vehicles (at least five) around the cells, dramatically increased in the OVA group by 5.5 fold (63.50% ± 15.51% vs phosphate-buffered saline 11.15% ± 8.26%, P < 0.001) and fell by 65% after PD treatment (21.95% ± 4.37% vs OVA 63.50% ± 15.51%, P < 0.001). PD mediated attenuation of mast cell degranulation was further confirmed by decreased histamine levels in both serum (5.98 ± 0.17 vs OVA 6.67 ± 0.12, P < 0.05) and intestinal mucosa homogenates (5.83 ± 0.91 vs OVA 7.35 ± 0.97, P < 0.05). Furthermore, we demonstrated that administration with PD significantly decreased mast cell degranulation due to reduced Ca(2+) influx through store-operated calcium channels (SOCs) (2.35 ± 0.39 vs OVA 3.51 ± 0.38, P < 0.01). Taken together, our data indicate that PD stabilizes mast cells by suppressing intracellular Ca(2+) mobilization, mainly through inhibiting Ca(2+) entry via SOCs, thus exerting a protective role against OVA-sensitized food allergy.World Journal of Gastroenterology 07/2013; 19(25):3980-9. · 2.55 Impact Factor
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ABSTRACT: The prevalence of food allergy has increased dramatically during the last three decades, but currently there was no effective therapy except avoidance of allergen. This study aimed to investigate the effect of a modified Chinese herbal formula, Formula-3, on mast cell degranulation and the anti-allergic activity in both animal and cell models. With OVA-sensitized food allergic model in Brown-Norway rats, we checked tissue injury in the small intestines by H&E staining. The Th2 cytokine levels and IgE production in serum or supernatant of the intestinal mucosa homogenates were analyzed by ELISA. Meanwhile, rat peritoneal mast cell activation and degranulation were examined by Toluidine Blue Stain and the release of histamine was measured. Furthermore, the regulation of Formula-3 on Ca(2+) mobilization was investigated by probing intracellular Ca(2+) with fluo-4 fluorescence. The direct effect of Formula-3 on mast cell stabilization was also studied in RBL-2H3 cell line. In vivo Formula-3 administration significantly reduced tissue damage in the small intestines of rat and suppressed Th2 cytokine secretion and IgE production. We demonstrated that Formula-3 treatment significantly suppressed FcεR1-mediated mast cell degranulation no matter in OVA-challenged allergic rats or IgE-sensitized RBL-2H3 cell line. Furthermore, Formula-3 significantly decreased Ca(2+) influx through store-operated calcium channels (SOCs) evoked by dinitrophenyl-BSA or thapsigargin in mast cells. Taken together, our data indicate that Formula-3 stabilizes mast cells by suppressing FcεR1-induced Ca(2+) mobilization mainly through inhibiting Ca(2+) entry via SOCs, thus exerting a protective effect against OVA-sensitized food allergy.International immunopharmacology 07/2013; · 2.21 Impact Factor
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ABSTRACT: Prostaglandins that constrict and relax airways are synthesized in reactions catalyzed by either COX-1 or COX-2. It is not known whether selective inhibition of COX-2 makes asthmatic responses better or worse. To determine the effects of the selective COX-2 inhibitor, etoricoxib, on allergen-induced bronchoconstriction in asthmatic subjects. Sixteen subjects with mild atopic asthma underwent rising dose inhalation challenges with allergen or methacholine to determine PD20 FEV1 during a control study period or after 10 to 13 days of treatment with etoricoxib (90 mg once daily). The order of study periods was randomized with at least 2-week washout periods. Induced sputum cells and fractional exhaled nitric oxide levels were used to assess airway inflammation and blood assays for COX-1 and COX-2 activity to assess enzyme inhibition. Urinary excretion of lipids was used to assess prostaglandin biosynthesis. Etoricoxib did not change baseline lung function, nor airway responsiveness to allergen or to methacholine. Neither were the allergen-induced increase in sputum eosinophils and fractional exhaled nitric oxide levels affected by treatment. The biochemical effectiveness of the treatment was established both in the blood assays and by the distinct inhibitory effect of etoricoxib on urinary excretion of tetranor-prostaglandin E2 (P < .001). This first study of COX-2 inhibition in provoked asthma found no negative effects of etoricoxib on allergen-induced airflow obstruction and sputum eosinophils, basal lung function, or methacholine responsiveness. The study suggests that short-term use of COX-2 inhibitors is safe in subjects with asthma.The Journal of allergy and clinical immunology 01/2014; · 12.05 Impact Factor