Effect of FK506 eye drops on late and delayed-type responses in ocular allergy models

Retinal transplant immunology and advancements

Several gaps and barriers remain for transplanting stem cells into the eye to treat ocular disease, especially diseases of the retina. While the eye has historically been considered immune privileged, recent thinking has identified the immune system as both a barrier and an opportunity for eye stem cell transplantation. Recent approaches leveraging scaffolds or cloaking have been considered in other tissues beyond immune suppression. This perspective paper outlines approaches for transplantation and proposes opportunities to overcome barriers of the immune system in stem cell transplantation in the eye.

Ocular redness - II: Progress in development of therapeutics for the management of conjunctival hyperemia

Conjunctival hyperemia is one of the most common causes for visits to primary care physicians, optometrists, ophthalmologists, and emergency rooms. Despite its high incidence, the treatment options for patients with conjunctival hyperemia are restricted to over-the-counter drugs that provide symptomatic relief due to short duration of action, tachyphylaxis and rebound redness. As our understanding of the immunopathological pathways causing conjunctival hyperemia expands, newer therapeutic targets are being discovered. These insights have also contributed to the development of animal models for mimicking the pathogenic changes in microvasculature causing hyperemia. Furthermore, this progress has catalyzed the development of novel therapeutics that provide efficacious, long-term relief from conjunctival hyperemia with minimal adverse effects.

Tacrolimus Ointment for Treatment of Vernal Keratoconjunctivitis

Purpose:

To evaluate the safety and efficacy of tacrolimus 0.1% ointment for the treatment of refractory vernal keratoconjunctivitis (VKC).

Materials and Methods:

This prospective, nonrandomized case series enrolled 20 patients (40 eyes) with severe VKC, who were treated with tacrolimus 0.1% ointment. The mean age of the patients was 18.25 ± 4.2 years (range, 9–31 years). Each patient completed a follow-up period of at least 24 months. The main outcome measure was the clinical response to treatment.

Results:

Significant improvements in clinical signs and symptoms were achieved in all patients 6 weeks after starting treatment with topical tacrolimus. Treatment was gradually reduced, with increasing intervals between applications. VKC recurred in all patients who attempted to discontinue treatment. No additional medications were required and no significant changes in visual acuity or refraction were documented. Five patients discontinued treatment due to a severe burning sensation and were excluded from the study.

Conclusions:

Tacrolimus, 0.1% ointment, is a safe and effective treatment for VKC refractory to standard treatment and may be used as a substitute for steroid treatments used to controlled disease activity. However, adverse effects could cause poor patient compliance.

Long-term follow-up of tacrolimus ointment for treatment of atopic keratoconjunctivitis

PURPOSE

To evaluate the long-term clinical outcomes of 0.1% tacrolimus dermatologic ointment (Protopic) in cases of refractory atopic keratoconjunctivitis (AKC).

DESIGN

Prospective, nonrandomized, noncontrolled case series.

METHODS

Twenty-two eyes from 11 patients with severe AKC who were treated with 0.1% tacrolimus ointment were followed prospectively. The mean age of the patients was 32.27 ± 12.7 years (range, 19-61 years). Each patient completed a follow-up period of at least 48 months, during which the signs and symptoms of AKC were assessed. Changes in the total scores of signs and symptoms from baseline were recorded at each visit, and the main outcome measure was the clinical response to topical tacrolimus treatment.

RESULTS

Dramatic improvements in clinical signs and symptoms were achieved 1 week after starting topical tacrolimus treatment, and complete clinical resolution was observed in almost all patients 6 weeks after starting treatment. Treatment was gradually reduced, with increasing intervals between applications. Eight patients remained asymptomatic for up to 3 years, although recurrence occurred in 3 patients who attempted to discontinue treatment. All patients complained of a mild burning sensation upon application of the ointment. No additional medications were required to provide relief, and no patient discontinued treatment because of adverse drug effects. No drug-related ocular complications were encountered, and no significant changes in visual acuity or refraction were documented.

CONCLUSIONS

Tacrolimus dermatologic ointment is a potentially safe and effective treatment for AKC cases refractory to standard treatment and may substitute for steroid treatments aimed at controlling disease activity.

Topical 0.005% tacrolimus eye drop for refractory vernal keratoconjunctivitis

PURPOSE

To evaluate the efficacy and safety of topical 0.005% tacrolimus eye drop for treatment of refractory vernal keratoconjunctivitis (VKC).

METHODS

This prospective study included 20 eyes of 10 patients with refractory VKC, who had active symptomatic disease despite conventional medications including topical steroids. After discontinuing all other medications, patients were treated with topical 0.005% tacrolimus eye drop four times a day. Changes in subjective symptoms and objective signs after treatment were evaluated, and development of possible complications was assessed.

RESULTS

Mean age of patients was 21.3±7.4 years and mean duration of VKC was 12.1±5.8 years. After starting tacrolimus eye drop, patients were followed for a mean duration of 10.7±3.7 months (range, 6-15 months). All symptoms including itching, redness, photosensitivity, foreign body sensation, and mucus discharge improved after the treatment; itching was the first symptom to show dramatic relief. In addition, there was improvement in objective signs including conjunctival hyperaemia, conjunctival papillary hypertrophy, giant papillae, limbal hypertrophy, corneal punctate epithelial erosions, and corneal pannus; conjunctival hyperaemia was the first sign to show improvement. No patient required addition of other medications including steroids for further relief. Any attempt to discontinue tacrolimus eye drop was associated with recurrence of patients' symptoms and signs, necessitating continued use of the medication during the entire follow-up time. No ocular complication related to tacrolimus was noted.

CONCLUSION

Topical 0.005% tacrolimus eye drop seemed to be a safe and effective treatment for steroid-resistant refractory VKC; however, long-term use was needed to control the disease.

Optical fiber-coupled ocular spectrometer for measurement of drug concentration in the anterior eye--applications in pharmaceuticals research

This paper describes in detail a novel optoelectronic system designed to measure drug absorption in the anterior segment of the eye following topical application of drug formulations. This minimally invasive measurement technique offers both a method for determining drug concentration in human eyes, and demonstrates an alternative to current testing processes in model animals, which require paracentesis of the anterior chamber of the eye. The optoelectronic technique can be used with formulations, which possess appropriate spectral characteristics, namely unique absorption or fluorescence spectra. Preliminary experiments using our measurement system have been performed in rabbit and man, where we have been successful in achieving the direct measurement of topically applied brimonidine, an alpha-2 agonist used in the treatment of glaucoma. This demonstrates the feasibility of performing real-time, in vivo testing of ophthalmic drug formulations in the eye of human test subjects. We further demonstrate the novel application of the optoelectronic system for detection of topically applied UV-absorbing compounds in rabbit cadaver eyes, with a view to evaluating potential ocular sunscreen formulations. In summary, this method can be applied for the rapid comparison of the penetration of different drug formulations into the anterior eye at greatly reduced cost and time.

Late-phase reaction in ocular allergy

PURPOSE OF REVIEW

To determine if the late-phase reaction, which commonly occurs in allergic rhinitis and asthma, is also found in ocular allergy.

RECENT FINDINGS

Using PubMed, 542 articles were found; 18 articles in the allergy and ophthalmology literature were specifically related to late-phase reaction. Ocular late-phase reaction is clinically seen in 50-100% of allergic rhinoconjunctivitis patients, is associated with progression to systemic atopic disorders that is allergic rhinoconjunctivitis and occurs in several forms including biphasic, multiphasic and a prolonged response.

SUMMARY

The existing literature demonstrates that an ocular late-phase reaction also exists and has implications in the development severity of disease, change of reactivity and progression of the atopic disease state from a localized target organ, such as the nose or eye, to a more systemic atopic disorder. The existence of the clinically relevant allergic late-phase response is not only limited to the nose, skin and lungs but also includes the eyes. The appreciation that the late-phase response may be clinically very important as there is a continuum of ocular mast-cell activation during the waking hours of the day, a better understanding of its clinical impact may be a more appropriate focus in the development of future treatments.

Pharmacokinetics and tissue distribution of tacrolimus (FK506) after a single or repeated ocular instillation in rabbits

PURPOSE

The aim of this study was to investigate the ocular distribution of tacrolimus (FK506) and absorption into the systemic circulation after a single or repeated topical instillation of FK506 ophthalmic suspension in male New Zealand white rabbits.

METHODS

In the single instillation study (group 1), 29.1-34.8 microL of a 0.1, 0.3, and 1% suspension was administered to each of the 15 rabbits. In the repeated instillation study (group 2), 27.1-39.5 microL of a 0.3% suspension was administered to 27 rabbits q.i.d. (i.e., at 3-h intervals) for 14 days. In the intravenous (i.v.) dose study (group 3), 1 mg/kg of FK506 was administered to 3 rabbits. The amount of FK506 was measured by using a competitive enzyme immunoassay.

RESULTS

The results for single and repeated instillation studies were similar. In the single instillation study, blood T(max) after an instillation of the 0.1, 0.3, and 1% suspensions (at 0.8, 1.0, and 1.0 hours) did not differ significantly among these doses. One (1) h after an instillation of the 1% suspension, ocular tissue concentrations, except the retina/choroid, vitreous body, and lens, were higher than the blood concentration (C(max): 2.7 ng/mL). In particular, concentrations in the conjunctiva, cornea, iris, and anterior sclera were much higher than the blood concentration (148, 900, 120, and 145 ng/g tissue). In the repeated instillation study, concentrations in the blood and ocular tissues (except the lens) reached a steady state by the 7th day. In the i.v. dose study, AUC(0-24h) and T(1/2) were 1643 ng h/mL and 18.5 h, respectively.

CONCLUSIONS

The high-level distribution of FK506 was observed in the conjunctiva, which is desirable because the conjunctiva is the target tissue for pharmacologic effect (i.e., efficacy).

Preliminary study of the effect of FK506 nanospheric-suspension eye drops on rejection of penetrating keratoplasty

OBJECTIVE

The aim of this study was to investigate the effect of a topical FK506 nanospheric suspension in a rat model of penetrating keratoplasty.

METHODS

FK506 nanospheres were prepared by using a biodegradable poly (lactic-co-glycolic acid) copolymer (PLGA). Its distribution in the eye and blood after a single instillation was examined in rabbits. Sprague-Dawley (SD) rats received corneal heterografts and were topically treated with phosphate-buffered saline (PBS), PLGA, FK-506 0.01% (nanospheres), or dexamethasone 0.05% solutions twice a day for 28 days. Rejection index and graft-survival time were recorded and compared between the four groups. Three grafts were collected at different time points for immunohistochemical studies.

RESULTS

In the cornea, the FK-506 concentration reached its peak within 1 h of a single eye-drop instillation and then decreased by half (1667.85 +/- 611.87 ng/g) at 8 h. FK-506 cannot be detected in rabbit blood. There were significant differences in the graft-survival time between the FK-506 nanosphere group (15.09 +/- 4.81 days) and the other three groups [PBS (7.90 +/- 1.20, t = -4.594, P < 0.001), PLGA (8.44 +/- 0.88, t = - 4.074, P = 0.001) and dexamethasone (10.44 +/- 1.42, t = -2.790, P = 0.012)]. The rejected corneas in the FK506 nanosphere group showed significantly fewer CD4, CD8, CD68, CD79, vascular endothelial growth factor, ICAM, and tumor growth factor-beta(1)-positive cells than those in the other groups.

CONCLUSIONS

FK506 0.01% nanospheric-suspension eye drops delayed the occurrence of corneal allograft rejection and prolonged allograft survival time. The FK506 nanospheres may be valuable in suppressing corneal graft rejection.

Effect of 0.03% tacrolimus ointment on conjunctival cytology in patients with severe atopic blepharoconjunctivitis: a retrospective study

PURPOSE

To evaluate the efficacy and effect of tacrolimus ointment on conjunctival cytology in patients with atopic blepharoconjunctivitis or keratoconjunctivitis.

METHODS

Ten patients with severe atopic blepharoconjunctivitis treated with 0.03% tacrolimus ointment once daily as an intermittent treatment were analysed retrospectively. The main outcome measures were clinical response to topical tacrolimus, adverse events and changes in the inflammatory cells obtained from conjunctival brush samples.

RESULTS

Marked clinical responses in blepharitis and conjunctivitis symptoms were seen after a mean follow-up time of 6 weeks. Clinical scores decreased by 67% in blepharitis and 74% in conjunctivitis symptoms. No severe adverse events or signs of immunosuppression such as herpes simplex infections occurred. No significant changes occurred in visual acuity, refraction, anterior chamber, retina or intraocular pressure. Median decreases were 85% (p =0.01) in conjunctival eosinophils, 50% (p = 0.01) in neutrophils and 58% (p = 0.02) in lymphocytes.

CONCLUSIONS

Tacrolimus ointment is potentially a safe and effective treatment for atopic blepharoconjunctivitis. Regular treatment of the eyelids once daily may also lead to clinical and cytological improvement of the conjunctivitis.

Cyclosporin A inhibits eosinophilic infiltration into the conjunctiva mediated by type IV allergic reactions

BACKGROUND

Eosinophils are important effector cells in severe allergic conjunctivitis such as vernal keratoconjunctivitis. Infiltration of eosinophils into the conjunctiva is mediated by type I and type IV allergic reactions. Cyclosporin A (CsA) eye drops are administered therapeutically for severe allergic conjunctivitis, but the mechanism by which CsA acts, that is, by inhibiting type I, type IV or both types of allergic reactions, is not known. We investigated whether CsA eye drops inhibit type I, type IV or both types of allergic reactions in the conjunctiva.

METHODS

Experimental immune-mediated blepharoconjunctivitis (EC) was induced in BALB/c mice by either active immunization or passive immunization by transfer of ragweed (RW)-primed splenocytes and RW-specific IgE, followed by RW challenge to the conjunctiva. These mice were treated in eye drops with vehicle, 0.1% CsA, 0.5% CsA or 0.1% betamethasone five times (1 and 2 h before RW challenge and 1, 2 and 3 h after RW challenge). Twenty-four hours after the challenge, the conjunctivas were harvested for histological analysis to evaluate eosinophilic infiltration. To evaluate effects of CsA eye drops on systemic immune responses, sera and spleens were collected from actively immunized mice at the time of sacrifice to examine serum IgE levels and cellular immune responses, respectively.

RESULTS

CsA eye drops significantly inhibited eosinophilic infiltration into the conjunctiva in actively immunized EC-developing mice compared with vehicle-treated mice. The CsA-induced inhibition was similar to inhibition induced by 0.1% betamethasone. Serum IgE levels and splenocyte responses in CsA-treated mice were equivalent to those in vehicle-treated mice. Betamethasone treatment inhibited eosinophilic infiltration into the conjunctiva induced by both splenocyte transfer and IgE transfer, while CsA treatment inhibited infiltration induced by splenocyte transfer.

CONCLUSIONS

CsA eye drops inhibited eosinophilic infiltration into the conjunctiva without affecting systemic immune responses. CsA predominantly inhibits eosinophilic infiltration by interfering with the type IV allergic reaction in the conjunctiva.

Emerging drugs for ocular allergy

Ocular allergy is a common condition that usually affects the conjunctiva of the eye and is, therefore, often referred to as allergic conjunctivitis. The severity of the disease can range from mild itching and redness, as seen in seasonal allergic conjunctivitis, to the more severe, sight-threatening forms such as vernal and atopic keratoconjunctivitis. The central mechanism in the pathogenesis of these diseases is IgE-mediated mast cell degranulation and activation of T lymphocytes, eosinophils and conjunctival structural cells. The pharmacotherapy of allergic conjunctivitis consists of several classes of drugs: antihistamines, mast cell stabilisers, dual-acting agents and corticosteroids. None of the available drugs completely abolishes the development of ocular allergy. For this reason, new topical antiallergic/anti-inflammatory agents are currently and continually under clinical trials. This review provides a background to ocular allergic diseases, the medical need for therapy and current and potential new treatments.

Traitement d’une localisation oculaire de pemphigoïde cicatricielle par tacrolimus topique

BACKGROUND

Ocular involvement in cicatricial pemphigoid often occurs from the onset. Certain forms are seen only in this condition.

OBSERVATION

A 31-year-old woman presented highly inflammatory conjunctivitis for several months associated with bilateral symblepharons and superficial punctuate keratitis around the left eye refractory to treatment. The patient had a history of mouth ulcers and sores on the scalp. Examination showed scalp lesions with crusts. Histological examination of these lesions revealed dermal-epidermal cleavage. Direct immunofluorescence showed sub-membrane deposits. Anti-basal membrane antibodies were positive. Immunotransfer confirmed the presence of circulating antibodies. This condition was controlled following administration of three courses of cyclophosphamide as a bolus. However, the symblepharons persisted in both eyes. Improvement lasted 4 years. The patient again consulted for inflammatory conjunctivitis and superficial punctate keratitis resulting in invalidating loss of visual acuity, associated with hypereosinophilia. Cortisone eye drops alone resulted in no improvement. Treatment was initiated with topical tacrolimus (Protopic) 0.03% comprising once-daily application to the conjunctiva in the evening. This therapy was well tolerated, and 2 daily applications could be given, followed by a dosage of 0.1%. Improvement was rapid and spectacular, with frank amelioration of visual acuity and resolution of the patient's keratitis. Treatment was continued for 4 months and gradually reduced to the 0.03% dosage level, with increasingly wide intervals between applications. There has been no relapse within the 12 months following the end of treatment.

DISCUSSION

Standard treatment of pharmacological cicatricial pemphigoid involves systemic immunosuppression since topical anti-inflammatories are ineffective. The mortality associated with this disease is due to iatrogenic complications. Tacrolimus exhibits extremely good penetration of the conjunctiva. Following administration at a concentration of 0.06% 3 times daily in 15 patients with inflammatory disease of the conjunctiva or the cornea, improvement was seen in 10 of these patients at 26 weeks. Tacrolimus appears to act through immunomodulatory and anti-inflammatory mechanisms. It induces local inhibition of T lymphocyte activation and reduces production of pro-inflammatory lymphokines. Oral tacrolimus cannot be used to control cicatricial pemphigoid refractory to standard immunomodulators. However, 3 three other cases involving topical treatment of cicatricial pemphigoid showed marked efficacy of treatment given for 2 to 6 months, with complete tolerability. Thus, topical tacrolimus appears to constitute an interesting alternative treatment in cicatricial pemphigoid.

FK506 aerosol locally inhibits antigen-induced airway inflammation in Guinea pigs

BACKGROUND

Eosinophilic airway inflammation is a common pathological feature of asthma. It has been shown that FK506 given systemically suppresses antigen-induced airway inflammation in animal models. However, it is unknown whether inhaled FK506 can suppress the airway allergic inflammation/immune response and whether it acts locally or systemically.

METHODS

We tested the effects of oral FK506 and inhaled FK506 on antigen-induced airway inflammation in guinea pigs. The tissue and blood concentrations of FK506 given via both routes were compared. The effect of inhaled FK506 on the expression of cytokine mRNA in lung and bronchoalveolar lavage fluid (BALF) cells was also tested.

RESULTS

Both routes of administration of FK506 suppressed the airway eosinophilia in egg albumin (EA)-sensitized and -challenged animals. The effect of three inhaled puffs was almost equal to that of 1 mg/kg administered by the oral route. Following inhalation of three puffs, FK506 concentration in blood (AUC(0-24 h)) was approximately 1/21 of that following oral FK506 (1 mg/kg). After EA challenge, mRNA expression of interleukin (IL)-5, eotaxin and IL-1beta in BALF cells and IL-5 in the lung increased significantly. FK506 aerosol markedly inhibited IL-5 mRNA expression in the lung. In situ hybridization indicated that in the BALF IL-5 mRNA expression by lymphocyte-like cells was inhibited by FK506 aerosol. In addition, anti-IL-5 antibody injected intratracheally almost completely abolished eosinophilia in this model.

CONCLUSION

Inhaled FK506 can suppress airway inflammation in guinea pigs, where the local action, presumably the inhibition of T-cell activation/function in the lung and airways, was primarily important.