Allergen dose response and late symptoms in a human model of ocular allergy

Anti-inflammatory and antiallergic effects of ketorolac tromethamine in the conjunctival provocation model

AIM

To study the effect of the topical anti-inflammatory drug, ketorolac, on (1) the clinical allergic reaction induced by the conjunctival provocation test (CPT); (2) the release of tryptase in tears; and (3) the expression of adhesion molecules on the conjunctival epithelium.

METHODS

10 allergic but non-active patients were challenged in both eyes with increasing doses of specific allergen to obtain a positive bilateral reaction and rechallenged, after 1 week, to confirm the allergic threshold dose response. After 2 weeks, a third CPT was then performed bilaterally 30 minutes after topical application of ketorolac in one eye and placebo in the contralateral eye in a double blind fashion. Clinical symptoms and signs were registered 5, 10, 15, and 20 minutes after challenge. The following objective tests were performed: tear tryptase measurement; tear cytology; and conjunctival impression cytology for immunohistochemical expression of ICAM-1 on epithelial cells.

RESULTS

Compared with placebo, ketorolac significantly reduced the total clinical score and the itching score in the 20 minutes after challenge (p<0.0005). Tear levels of tryptase were significantly reduced in the ketorolac pretreated eyes compared with placebo (p<0.03). Eosinophils, neutrophils, and lymphocytes in tear cytology were significantly lower in ketorolac treated eyes compared with placebo. A significant difference in the epithelial expression of ICAM-1 was observed between placebo and ketorolac treated eyes (p<0.05).

CONCLUSION

Ketorolac proved to be effective in reducing mast cell degranulation, as indicated by significantly decreased tryptase tear levels, as well as the clinical and cytological allergic reaction.

Nasal response to a single antigen challenge in patients with allergic rhinitis - inflammatory cell recruitment persists up to 48 hours

BACKGROUND

Allergen challenge in some patients with respiratory allergy is followed by an early and a late reaction.

OBJECTIVE

To evaluate the duration of mediator release and inflammatory cell recruitment during the late antigen-induced nasal response.

METHODS

Eight patients with seasonal allergic rhinitis due to grass pollen underwent local challenge with the relevant allergen, a non-relevant allergen (Parietaria judaica), and nebulized saline solution. Nasal lavages were performed at baseline and 6, 24, 48, 72 h after challenge. Eosinophil cationic protein (ECP), leukotriene C4 (LTC4), leukotriene B4 (LTB4) myeloperoxidase (MPO) and prostaglandin D2 (PGD2) levels were radioimmunoassayed and histamine concentration was measured by an automated fluorometric method.

RESULTS

Nasal challenge with the relevant antigen induced a response 6 h after stimulation, which subsided within 24 h. Eosinophilia, observed in the nasal lavages collected from 6 to 24 h after this challenge, was accompanied by ECP release. Neutrophilia were found in the nasal lavages collected from 6 to 24 h after challenge. The increase in neutrophil number correlated with MPO levels and LTB4 concentrations, but not with the intensity of nasal obstruction. Antigen challenge also induced significant recruitment of mononuclear cells 48 h after provocation. The challenge significantly raised histamine, but not PGD2, levels in the nasal lavages collected 6 h after provocation. A trend towards an increase in LTC4 levels in the nasal lavages collected 6 h after specific antigen challenge was also found. Nasal challenge with a non-relevant allergen or with saline solution did not cause either inflammatory cell recruitment or mediator release.

CONCLUSION

Nasal challenge with the relevant antigen can induce a late response characterized by local accumulation of eosinophils, neutrophils and mononuclear cells persisting for 48 h and accompanied by release of ECP, MPO, LTB4 and histamine. These results indicate that a single antigen challenge in patients with allergic rhinitis causes prolonged inflammatory alterations which may contribute to the development of airway hyperreactivity.

Tumour necrosis factor alpha (TNFalpha) in tears of atopic patients after conjunctival allergen challenge

BACKGROUND

Proinflammatory cytokines, such as TNFalpha are involved in the pathogenesis of allergic rhinitis and asthma.

OBJECTIVE

Our aim was to study the tear fluid TNFalpha levels in atopic patients before and after topical ocular allergen challenge.

METHODS

Thirteen patients were first challenged with topical allergen in the left eye and then dilution buffer in the right eye. Tear fluid samples were collected before the challenges and after 5, 30 and 60 min. Clinical symptoms were scored. Tear fluid TNFalpha concentrations were measured using a double-antibody radioimmunoassay. TNFalpha release rates were calculated using the tear fluid flow in the collection capillary as an estimate for the tear secretion rate.

RESULTS

The mean baseline TNFalpha concentrations (ng/L) were 1310 (allergen-challenged eye) and 967 (control eye), and release rates (pg/min) 1.81 (allergen-challenged eye) and 1.39 (control eye), respectively. In the allergen-challenged eye, TNFalpha concentrations and release rates were 1479 and 4.30 (5 min), 1367 and 3.20 (30 min) and 1426 and 3.80 (60 min). In the control eye, TNFalpha concentrations and release rates were 746 and 0.67 (5 min), 1001 and 0.92 (30 min) and 1504 and 1.05 (60 min). The release rates of the allergen-challenged eye were significantly increased at all time points after the challenge when compared with the baseline or the control eye.

CONCLUSION

Increased TNFalpha release rates suggest that this cytokine is an early mediator of allergy after conjunctival challenge.

Characterization of antihistamines using biphasic cutaneous reaction in BALB/c mice

Effects of 11 histamine H1 receptor antagonists on IgE-mediated biphasic cutaneous reaction in mice were examined. The immediate phase reaction (IPR) assessed at 1 hour after antigen application was significantly inhibited by all antihistamines examined. The inhibition of IPR by cetirizine and mequitazine were potent, but those by cyproheptadine and diphenhydramine were weak. The later phase reaction (LPR) assessed at 24 hours after antigen application was inhibited by chlorpheniramine, oxatomide, ketotifen, mequitazine, emedastine, terfenadine and azelastine. The inhibition of LPR by emedastine was potent, but those by ketotifen and terfenadine were only partial. Emedastine inhibited both IPR and LPR comparably. Present results indicate that H1 receptor activation is involved in the IPR of the biphasic cutaneous reaction, and that the blockade of H1 receptors at IPR does not contribute to the attenuation of following LPR. Histamine H1 receptor antagonists inhibiting the LPR have a property distinct from H1 receptor antagonism, which may have an additional benefit for the treatment of allergic diseases.

Efficacy of lodoxamide eye drops on mast cells and eosinophils after allergen challenge in allergic conjunctivitis

PURPOSE

The purpose of the study is to evaluate in a double-blind, randomized study the efficacy of lodoxamide tromethamine 0.1% versus placebo.

METHODS

Signs and symptoms, tear tryptase, and tear fluid cytology were evaluated in 20 asymptomatic subjects with allergic conjunctivitis. The study included three allergen challenges in skin test-positive patients. At the first visit, a threshold dose of allergen was established. At the second visit, a bilateral ocular challenge was performed without pretreatment. At the third visit, either lodoxamide or placebo eye drops were used for 1 week before ocular challenge.

RESULTS

Lodoxamide significantly reduced tryptase levels (P < 0.01), neutrophils (P < 0.04), and eosinophils (P < 0.01) in the tear fluid and significantly inhibited ocular itching (P < 0.02) when compared with that of placebo.

CONCLUSIONS

Lodoxamide is effective in reducing tryptase levels and the recruitment of inflammatory cells in the tear fluid after allergen challenge.

The eosinophil and the eye

Personal studies in allergic eye diseases reviewed in this paper indicate that: 1. An increased number and an abnormal distribution of eosinophils is present in conjunctival biopsies of patients with vernal keratoconjunctivitis (VKC). 2. Eosinophil and eosinophil products, such as ECP, are also increased in tears of VKC patients and, in hay fever conjunctivitis, accumulate during the late-phase of allergic reaction following specific allergen challenge. 3. Circulating eosinophils of VKC patients show a typical activation phenotypic profile which is associated with increased serum level of eosinophil cationic protein and eosinophil-derived neurotoxin/protein X. A clinical study of the modulatory effect of cetirizine on the early and late phase of the allergic reaction as well as on the eosinophil activation and tissue recruitment following conjunctival allergen challenge is reported as an example of the need to evaluate eosinophil functions when investigating anti-allergic drugs. Drugs modulating various aspects of eosinophil function could play a primary role in the treatment of allergic eye disease.

Effect of prednisolone on IgE-dependent biphasic cutaneous reaction in BALB/c mice

1. The effect of prednisolone on IgE-dependent, antigen-induced biphasic cutaneous reaction in BALB/c mice was investigated. 2. The biphasic cutaneous reaction with peak responses at 1 h and 24 h after antigen stimulation was suppressed by prednisolone administered 2 h before the challenge. 3. Although antigen challenge increased the expression of IL-1 beta and TNF-alpha mRNA in the mouse ear, prednisolone did not affect the increase. 4. Anti-IL-1 beta antibodies inhibited the later phase of biphasic cutaneous reaction, whereas anti-TNF-alpha antibodies inhibited both phases of the reaction. 5. Prednisolone inhibited edematous reactions caused by both IL-1 beta and TNF-alpha. 6. Proinflammatory cytokines, such as IL-1 beta and TNF-alpha, participate in the development of the biphasic cutaneous reaction, especially in its later phase, in mice, and prednisolone inhibits the reaction by suppressing the action of cytokines, at least in part.

Tear tryptase levels and allergic conjunctivitis

We measured tryptase, a neutral protease stored in the secretory granules of mast cells, by solid-phase radioimmunoassay in tears of 12 subjects with vernal keratoconjunctivitis (VKC) during remission phases, nine subjects with seasonal or perennial allergic conjunctivitis, and eight healthy controls. Mean values of tear tryptase levels were significantly (P < 0.02) increased in VKC patients (14.5 +/- 13 micrograms/l) when compared to those measured in patients with seasonal or perennial allergic conjunctivitis (0.6 +/- 0.1 microgram/l) and in controls (3.3 +/- 3.2 micrograms/l). In subjects with allergic conjunctivitis, the levels of tryptase, almost undetectable before allergen conjunctival challenge, showed a significant increase in the challenged eye 20 min-but not 6 h-after provocation in 5/9 cases. Our results indicate that VKC a severe ocular disease characterized by an increased number and abnormal distribution of mast cells in the conjunctiva, also shows elevated levels of tryptase in tears even during remission phases. Evidence of mast-cell activation, as revealed by a significant increase of tryptase levels in tears, in documented during the early-phase reaction, but not during the late-phase reaction, of allergic conjunctivitis patients challenged topically by specific allergen.

Eosinophil cationic protein in tears in allergic conjunctivitis

AIMS/BACKGROUND--Eosinophil cationic protein (ECP) is a quantifiable product secreted by activated eosinophils. The aim of this study was to assess the degree of eosinophil activity in different clinical stages of various forms of allergic conjunctivitis. METHODS--Tears were collected in glass capillary tubes from 14 subjects with seasonal allergic conjunctivitis (SAC), 23 subjects with vernal keratoconjunctivitis (VKC), 16 subjects with atopic keratoconjunctivitis (AKC), 10 subjects with giant papillary conjunctivitis (GPC), and 16 healthy control subjects. The samples were analysed in duplicate with a radio-immunoassay for ECP. RESULTS--Statistically significant differences were evident between healthy controls and allergic subjects (p < 0.001). Subjects with AKC and VKC had significantly higher tear ECP values than subjects with GPC and SAC. In addition, there was a significant correlation between ECP values and disease severity in all disorders. CONCLUSION--The data suggest a particular pathogenic role of the eosinophil in VKC and AKC, and a less pronounced but still important eosinophil involvement in the disease processes of GPC and SAC.

Cetirizine reduces inflammatory cell recruitment and ICAM-1 (or CD54) expression on conjunctival epithelium in both early- and late-phase reactions after allergen-specific challenge

BACKGROUND

Allergen-specific conjunctival challenge (ASCC) is a safe and reproducible experimental model of allergic conjunctivitis and a useful tool in the evaluation of effectiveness and possible mechanisms of action of drugs commonly used in the treatment of allergic diseases.

OBJECTIVE

The protective effect of cetirizine on inflammatory changes after ASCC was assessed in 12 patients with rhinoconjunctivitis caused by Parietaria judaica in a double-blind study.

METHODS

After a screening ASCC was performed, patients were randomized into two treatment groups; each patient was given cetirizine (oral tablets) 10 mg twice daily, or matching placebo for 3 1/2 days in off-pollen season. Clinical evaluation (itching, hyperemia, lacrimation, and swelling of eyelids) and cytologic assessment (number of inflammatory cells in conjunctival scraping and evaluation of intercellular adhesion molecule-1 (ICAM-1)/CD54 expression on epithelial cells) were performed at baseline, 30 minutes (i.e., early-phase reaction [EPR]), 6 hours, and 24 hours (i.e., late-phase reaction [LPR]) after ASCC, before and after treatment.

RESULTS

The EPR clinical events and the EPR total number of inflammatory cells were significantly reduced by cetirizine compared with placebo. The LPR clinical events and inflammatory cell recruitment were reduced by cetirizine in a similar manner. Both eosinophil and neutrophil numbers were decreased by active drug in EPR and LPR. Furthermore, ICAM-1/CD54 expression was significantly reduced by cetirizine in both the EPR and LPR compared with placebo.

CONCLUSIONS

This study shows that cetirizine has a protective effect on clinical and cellular EPR and LPR events (including ICAM-1/CD54 expression on epithelium) induced by ASCC.

The eye and the eosinophil

Recent work has highlighted the eosinophil's role as an effector cell in a wide array of disease entities, including parasitic infections and allergic and nonallergic diseases. The eosinophil is filled with granules containing toxic cationic proteins, capable of harming tissue when released to the extracellular space. In the eye, toxic eosinophil cationic granule proteins have been encountered in conjunctiva, cornea, tears, and contact lenses of patients suffering from ocular allergy, suggesting an effector role for the eosinophil in the ophthalmic manifestations of atopy. Laboratory investigations indicate that eosinophil granule major basic protein, the principal eosinophil granule protein, may adversely influence corneal epithelium, and promote corneal ulceration in the severest forms of ocular allergy. Further, the eosinophil may play a contributory pathophysiologic role in some nonallergic ophthalmic diseases such as Wegener's granulomatosis, orbital pseudo-tumor, and histiocytosis X. The eosinophil's morphologic, immunologic, and biochemical characteristics will be reviewed and its role in certain ophthalmic diseases thoroughly examined.

Evidence of intercellular adhesion molecule-1 expression on nasal epithelial cells in acute rhinoconjunctivitis caused by pollen exposure

Rhinoconjunctivitis caused by pollen allergy is characterized by typical signs and symptoms and mucosal infiltration by inflammatory cells during pollen season. It has been recently demonstrated that the adhesion molecule system is deeply involved in cell-to-cell interaction during inflammatory response consequent to allergic reactions. The aim of this study was to evaluate the expression of intercellular adhesion molecule-1 (ICAM-1 or CD54) on nasal epithelial cells, before and during natural seasonal exposure, in 10 allergic patients (Parietaria judaica-sensitized) and in 10 healthy volunteers, correlating this parameter with clinical and cytologic involvement. Nasal epithelial cells of allergic subjects showed a significant expression of CD54 during pollen season (p < 0.001). On the contrary, no CD54 expression was observed out of pollen season. In healthy volunteers no CD54 expression was observed both before and during pollen season. Cytologic evaluation demonstrated an infiltration by eosinophils (mainly activated [EG2+]), (p < 0.001), neutrophils (p < 0.001), and metachromatic cells (p < 0.001) during pollen season only in allergic subjects. Therefore results indicate that seasonal allergic rhinitis is characterized by an infiltration of inflammatory cells correlated with CD54 expression on nasal epithelial cells. This phenomenon is specific, being restricted only to allergic patients during pollen season.

Nedocromil sodium 2% eye drops for twice-daily treatment of seasonal allergic conjunctivitis: a Swedish multicentre placebo-controlled study in children allergic to birch pollen

This was a multicentre, double-blind, randomized group comparative study in which 77 children, aged 6-16 years, received 2% nedocromil sodium eye drops and 72 received placebo, one drop into each eye twice daily. The treatment period was 4 weeks, covering the peak birch pollen season. Prior to the start of the season, patients who had attended the clinic the previous 2 years because of seasonal allergic conjunctivitis (SAC) to birch pollen, entered a one week baseline period during which symptoms were assessed, dairy cards completed, and routine sampling of blood and urine carried out. The double-blind treatment period then commenced at the onset of the birch pollen season. Patients/parents kept daily diary record cards of eye symptom severity and concomitant therapy. Conjunctivitis was mild in both treatment groups but nedocromil sodium was more effective than placebo in controlling symptoms. During the 2-3 weeks of peak pollen counts, this therapeutic effect was statistically significant for itching (P < 0.01), watering (P < 0.05) and total symptom score (P < 0.01), but was not significant for grittiness (P = 0.08) or redness (P = 0.06). Global opinions of efficacy showed no difference between treatments, due to a high placebo effect (however, the diary card data indicated a significant improvement with nedocromil sodium). We therefore conclude that nedocromil sodium 2% eye drops, administered twice daily, is an effective treatment for SAC in children.

Adhesion molecules of allergic inflammation: recent insights into their functional roles

Canonica GW, Ciprandi G, Buscaglia S, Pesce G, Bagnasco M. Adhesion molecules of allergic inflammation: recent insights into their functional roles.

A three-year double-blind placebo-controlled study with specific oral immunotherapy to Dermatophagoides: evidence of safety and efficacy in paediatric patients

Very few double-blind trials of oral immunotherapy have been reported. The majority of these have been performed with pollen extracts and the results have often been equivocal. The major weaknesses of these studies have been the short periods of the trials, the low doses of allergen employed and inadequate evaluation of efficacy. The present study has involved a placebo-controlled double-blind trial of oral immunotherapy for three years with Dermatophagoides pteronyssinus at relatively high doses in 18 paediatric patients. Throughout the trial clinical parameters (symptom and medication scores) and immunological parameters (specific IgE, IgG1 and IgG4 levels) were monitored in order to assess the safety and efficacy of the treatment. The treatment was well tolerated by all patients and no side-effects were experienced. Clinical improvement was evident after the second year of therapy and this was confirmed by a significant reduction in conjunctival reactivity assessed by a specific conjunctival provocation test. In addition, there were significant changes in the immunological parameters with a reduction in specific IgE and increased levels of IgG4 and IgG1, results in keeping with previous studies of oral and subcutaneous immunotherapy. Although the results do not provide an explanation of the basis of successful oral immunotherapy, they clearly demonstrate the efficacy and safety of the treatment and suggest that it may be a useful and more acceptable alternative for patients than the traditional subcutaneous immunotherapy.

Deflazacort protects against late-phase but not early-phase reactions induced by the allergen-specific conjunctival provocation test

The protective effects of deflazacort against the inflammation that follows the conjunctival provocation test (CPT) by specific allergen were assessed in 24 patients with rhinoconjunctivitis caused by Parietaria judaica in a double-blind study. After a screening CPT, patients were randomized into four treatment groups, each being given deflazacort (oral tablets) at 6, 30, and 60 mg once daily, or matching placebo, for 3 d, outside the pollen season. Clinical evaluation (itching, hyperemia, lacrimation, and swelling of eyelids) and cytologic assessment (number of inflammatory cells in conjunctival scraping and evaluation of ICAM (intercellular adhesion molecule)-1/CD54 expression on epithelial cells) were performed at base line, 30 min (early-phase reaction (EPR), 6 h and 24 h (late-phase reaction (LPR)) after specific CPT, and before and after treatment. Neither the EPR clinical reactions nor the EPR total number of inflammatory cells was modified by deflazacort. However, the LPR clinical effects were significantly reduced by deflazacort at 30 or 60 mg/d (P < 0.01), as compared with placebo. The total number of inflammatory cells during LPR was significantly reduced by deflazacort at 30 or 60 mg/d (P < 0.01), as compared with placebo. Furthermore, CD54 expression was significantly reduced by deflazacort at 30 or 60 mg/d both in the EPR (P < 0.01) and LPR (P < 0.01), as compared with placebo. None of the studied indicators were modified at the 6 mg/d dose. This study shows that deflazacort has a highly protective action against clinical and cellular LPR effects induced by the specific CPT. In addition, deflazacort markedly reduces CD54 expression on the conjunctival epithelium during both EPR and LPR.

Conjunctivitis of allergic origin: immunologic mechanisms and current approaches to therapy

The pathogenesis of ocular allergy involves multiple mechanisms, which lead to mast cell degranulation and the release of chemical mediators. Mast cell mediators that have been implicated in allergic ocular disease include histamine, eosinophil chemotactic factors, eosinophil granule major basic protein, platelet-activating factor, prostaglandin D2, and several other less well-defined preformed or newly synthesized mediators. The release of these chemical mediators ultimately results in conjunctival vasodilation, increased vascular permeability, leukocyte chemotaxis, and, rarely, ocular surface destruction. Current therapy of ocular allergy involves elimination of the offending allergen, modulation of the immune system, and pharmacologic inhibition of the chemical mediators. The purpose of this article is to provide a better understanding of the pathogenesis and current therapy of ocular allergic disorders and to review the central role of the mast cell and chemical mediators involved in ocular allergy.

Protective effects of deflazacort on allergen-specific conjunctival challenge

The protective effects of deflazacort, (a new heterocyclic glucocorticoid and derivative of prednisolone, with calcium and glucose-sparing effects) on the inflammatory reaction following an allergen-specific conjunctival provocation test (CPT) were assessed in a double-blind study, in 24 patients suffering from rhinoconjunctivitis due to Parietaria judaica. After an initial screening CPT, patients were randomized to four treatment groups, to receive deflazacort, 6, 30 or 60 mg, once daily or placebo, for 3 days, during the low-pollen season. Clinical evaluations (itching, hyperaemia, lacrimation and eyelid swelling), cytological assessment (number of inflammatory cells, i.e. neutrophils, eosinophils and lymphocytes, sampled by conjunctival scraping) and immunocytochemical evaluation of CD54 (intercellular adhesion molecular-1 [ICAM-1]) expression on epithelial cells were performed after CPT, at baseline, after 30 minutes (early-phase reaction [EPR]) and after 6 and 24 hours (late-phase reaction [LPR]), before and after treatment. Neither the nature or severity of clinical events nor the total number of inflammatory cells during the EPR changed during treatment with deflazacort. The severity of the clinical events during the LPR were significantly reduced by deflazacort, 30 and 60 mg/day P < 0.01) compared to the placebo-treated group. The total number of inflammatory cells during the LPR was also significantly reduced by deflazacort, 30 and 60 mg/day (P < 0.01) compared to the placebo-treated group. CD54 expression was significantly reduced by deflazacort, 30 and 60 mg/day both during the EPR (P < 0.01) and LPR (P < 0.01) compared to the placebo-treated group.(ABSTRACT TRUNCATED AT 250 WORDS)

Nedocromil sodium and astemizole, alone or combined, for treatment of seasonal allergic conjunctivitis (SAC)

SAC is caused by allergen interaction with IgE antibody on conjunctival mast cells, leading to local release of vasoactive inflammatory mediators such as histamine. Nedocromil sodium both stabilizes mast cells and has antiinflammatory activity against other cells involved in allergic inflammation. Astemizole is a second generation orally-active H(1)-receptor antagonist with reduced CNS effects such as drowsiness. This multicentre, double blind, double dummy trial compared efficacy and safety of qid 2% nedocromil sodium eye drops with once daily 10 mg oral astemizole, placebo, and combined active treatments for a four-week period. SAC patients (n=207, aged 6-70 years) recorded their symptoms each day on diary cards. Signs and symptoms were also evaluated by clinicians after one, two and four weeks and overall opinions were recorded at the end of treatment. Nedocromil sodium eye drops and astemizole, alone or combined, significantly reduced ocular symptoms compared to placebo (for diary card total symptom score and patients' opinion). Clinicians' opinion showed significantly decreased symptoms with nedocromil sodium, alone or combined, but not with astemizole alone. All treatments were well tolerated, with drowsiness the most frequent side effect observed in patients treated with astemizole. These results demonstrate the effectiveness of nedocromil sodium eye drops in the treatment of SAC.