Effects of multiple dexamethasone treatments on aggravation of allergic conjunctivitis associated with mast cell hyperplasia

Stimulus-selective regulation of human mast cell gene expression, degranulation and leukotriene production by fluticasone and salmeterol

Despite the fact that glucocorticoids and long acting beta agonists are effective treatments for asthma, their effects on human mast cells (MC) appear to be modest. Although MC are one of the major effector cells in the underlying inflammatory reactions associated with asthma, their regulation by these drugs is not yet fully understood and, in some cases, controversial. Using a human immortalized MC line (LAD2), we studied the effects of fluticasone propionate (FP) and salmeterol (SM), on the release of early and late phase mediators. LAD2 cells were pretreated with FP (100 nM), SM (1 µM), alone and in combination, at various incubation times and subsequently stimulated with agonists substance P, C3a and IgE/anti-IgE. Degranulation was measured by the release of β-hexosaminidase. Cytokine and chemokine expression were measured using quantitative PCR, ELISA and cytometric bead array (CBA) assays. The combination of FP and SM synergistically inhibited degranulation of MC stimulated with substance P (33% inhibition compared to control, n = 3, P<.05). Degranulation was inhibited by FP alone, but not SM, when MC were stimulated with C3a (48% inhibition, n = 3, P<.05). As previously reported, FP and SM did not inhibit degranulation when MC were stimulated with IgE/anti-IgE. FP and SM in combination inhibited substance P-induced release of tumor necrosis factor (TNF), CCL2, and CXCL8 (98%, 99% and 92% inhibition, respectively, n = 4, P<.05). Fluticasone and salmeterol synergistically inhibited mediator production by human MC stimulated with the neuropeptide substance P. This synergistic effect on mast cell signaling may be relevant to the therapeutic benefit of combination therapy in asthma.

Comparison of the effects of topical cyclosporine a 0.05%, cyclosporine a 2%, epinastine hydrochloride 0.05%, and prednisolone acetate 1% on allergic inflammation in an experimental allergic conjunctivitis model

PURPOSE

To investigate the effects of topical cyclosporine A 0.05%, cyclosporine A 2%, epinastine hydrochloride 0.05%, and prednisolone acetate 1% in an experimental allergic conjunctivitis model.

METHODS

Forty Wistar albino male rats were randomly divided into 5 groups. All the rats were immunized by an intraperitoneal injection of 100 μg of ovalbumin. After 2 weeks, topical treatment was administered: cyclosporine A 0.05% 4 times a day to group 1, cyclosporine A 2% 4 times a day to group 2, epinastine HCl 0.05% 2 times a day to group 3, and prednisolone acetate 1% 4 times a day to group 4 for the following 7 days. Group 5 was designated as the control group. Both eyes of the rats were enucleated on the 22nd day of the study. The excised sections were stained by toluidine blue for mast cell count and by hematoxylin-eosin for histopathological evaluation.

RESULTS

The 2 solutions of cyclosporine A and epinastine were more effective than prednisolone acetate (P < 0.05) when compared with the control in histopathological scoring. There were statistically significant differences between the treatment groups and the control group (P < 0.05); however, no differences were observed between the treatment groups in the mast cell number.

CONCLUSIONS

Topical 0.05% cyclosporine A is as effective as 2% cyclosporine A and epinastine in suppressing mast cell-mediated type I allergic conjunctivitis in an experimental allergic conjunctivitis model.

Involvement of chymase in allergic conjunctivitis of guinea pigs

It has been reported that chymase activity was increased in allergic conjunctivitis patients and this activity was correlated with the severity of the disease. However, the precise roles of chymase in allergic conjunctivitis are unclear, and whether chymase inhibitors are effective for allergic conjunctivitis has not been reported even in experimental animal models. In this study, the roles of chymase in the pathogenesis were evaluated using a selective chymase inhibitor, ONO-WH-236, in a guinea pig model of allergic conjunctivitis induced by cedar pollen. Sensitized guinea pigs were challenged by the pollen, followed by assessing redness and edema in the conjuntiva, and counting the frequency of eye scratching as an itch-associated response. Treatment with the ONO-WH-236 (40 and 80 mg/kg, p.o.) dose-dependently inhibited the induction of redness, edema and scratching behavior. An anti-histaminic drug, ketotifen (3 mg/kg, p.o.), also significantly inhibited conjunctivitis symptoms. Chymase activity was increased in ophthalmic lavage fluid immediately after the pollen challenge. The increase in chymase activity was inhibited by in vivo treatment with ONO-WH-236. Interestingly, increased histamine in the ophthalmic lavage fluid immediately after the challenge was also inhibited by the chymase inhibitor. Administration of human recombinant chymase by eye dropping (0.09 and 0.9 μg/eye) dose-dependently induced scratching behavior, which was inhibited by not only ONO-WH-236 but also ketotifen; however, chymase administration induced only weak redness in the conjunctiva, which was resistant to treatment with anti-histaminic drugs. In conclusion, it was suggested that chymase was released from mast cells after antigen challenge, followed by the induction of conjunctivitis symptoms through histamine release from mast cells. Thus, chymase could be a potential target for pharmacotherapy for allergic conjunctivitis.

Effect of glucocorticoids on aquaporin-1 in guinea pigs with otitis media with effusion

The aim of this study was to explore the pathological changes in water homeostasis and the effects of glucocorticoids on aquaporin-1 (AQP1) in guinea pigs with otitis media with effusion (OME). Immunohistochemistry and western blotting were used to detect AQP1 in the bullae of OME models, which were induced by reversible Eustachian tube (ET) obstruction. Animals in the dexamethasone (dexa) group received dexa via intraperitoneal injection for 7 days and the pathological changes and expression patterns of AQP1 were compared with those in the OME group. In this study, 22 guinea pigs exhibited effusion 3–7 days after surgery, of which two were sacrificed. Six (60%) animals in the OME group and 9 (90%) in the dexa group presented no sign of effusion on postoperative day 14. AQP1 was detected as an 28-kDa protein in the two groups. Immunohistochemical analysis revealed that AQP1 was expressed in subepithelial fibroblasts and capillary endothelial cells. Western blot analysis revealed that the levels of AQP1 protein were markedly higher in the dexa group compared with the OME group. In conclusion, our study emphasized the significance of AQP1 in the pathophysiology of OME and suggests that glucocorticoids may regulate water homeostasis via an AQP1-regulated pathway.

Effect of Ganoderma lucidum on pollen-induced biphasic nasal blockage in a guinea pig model of allergic rhinitis

Ganoderma lucidum (GL), an oriental medical mushroom, has been used in Asia for the prevention and treatment of a variety of diseases. However, the effect of GL on allergic rhinitis has not been well defined. The current study describes the inhibitory effect of GL on the biphasic nasal blockage and nasal hyperresponsiveness induced by repeated antigen challenge in a guinea pig model of allergic rhinitis. Intranasally sensitized guinea pigs were repeatedly challenged by inhalation of Japanese cedar pollen once every week. Ganoderma lucidum was orally administered once daily for 8 weeks from the time before the first challenge. The treatment with GL dose-dependently inhibited the early and late phase nasal blockage at the fifth to ninth antigen challenges. Furthermore, nasal hyperresponsiveness to intranasally applied leukotriene D₄ on 2 days after the eighth antigen challenge was also inhibited by the treatment with GL. However, Cry j 1-specific IgE antibody production was not affected by the treatment. In conclusion, we demonstrated that the pollen-induced biphasic nasal blockage and nasal hyperresponsiveness were suppressed by the daily treatment with GL in the guinea pig model of allergic rhinitis. These results suggest that GL may be a useful therapeutic drug for treating patients with allergic rhinitis.