Cyclosporine A in veterinary ophthalmology

Leptospiral antibody prevalence and surgical treatment outcome in horses with Equine Recurrent Uveitis (ERU) in Switzerland

OBJECTIVE

To evaluate leptospiral antibody prevalence in 65 horses with ERU and compare outcome in 36 surgically treated eyes (2010-2015).

PROCEDURES

Retrospective data analysis of horses with ERU (n = 65). C-value calculation with microagglutination assay titer (MAT) results for Leptospira spp. Evaluation of follow-up data after pars plana vitrectomy (PPV, n = 21 eyes) and suprachoroidal cyclosporine device implantation (SCDI, n = 15 eyes). Differences between groups were statistically analyzed using Fishers exact test, significance set at P < .05.

RESULTS

Positive leptospiral titers were found in 28/65 blood, 31/65 aqueous humor (AH), and 19/20 vitreal (post-PPV) samples. The most common intraocular serovars were Leptospira interrogans grippotyphosa, pomona, and bratislava. Intraocular antibody production was suspected in samples of 22 horses (c-values > 1). Mean follow-up of surgical cases was 3.8 years (PPV) and 3.4 years (SCDI). PPV was performed in 21 eyes with positive, SCDI in 15 eyes with negative leptospiral test results. Uveitis recurred less often after PPV (2/21) compared to SCDI (6/15, P = .04). Retinal detachment occurred after PPV only (5/21, SCDI 0/15, P = .06), whereas only SCDI-treated eyes were enucleated (PPV 0/21, SCDI 3/15, P = .06). Blindness or visual impairment was equally likely to occur in both treatment groups after surgery (PPV 7/21, SCDI 7/15, P = .5).

CONCLUSIONS

Leptospiral antibody prevalence is high in horses with ERU in Switzerland. Recurrence of uveitis is uncommon following PPV in the present study; an increased risk of retinal detachment exists. Enucleation is more often warranted in horses after SCDI in this study due to a higher uveitis recurrence.

Immunopathologic Effects of Prednisolone and Cyclosporine A on Feline Immunodeficiency Virus Replication and Persistence

Feline immunodeficiency virus (FIV) induces opportunistic disease in chronically infected cats, and both prednisolone and cyclosporine A (CsA) are clinically used to treat complications such as lymphoma and stomatitis. However, the impact of these compounds on FIV infection are still unknown and understanding immunomodulatory effects on FIV replication and persistence is critical to guide safe and effective therapies. To determine the immunologic and virologic effects of prednisolone and CsA during FIV infection, FIV-positive cats were administered immunosuppressive doses of prednisolone (2 mg/kg) or CsA (5 mg/kg). Both prednisolone and CsA induced acute and transient increases in FIV DNA and RNA loads as detected by quantitative PCR. Changes in the proportion of lymphocyte immunophenotypes were also observed between FIV-infected and naïve cats treated with CsA and prednisolone, and both treatments caused acute increases in CD4+ lymphocytes that correlated with increased FIV RNA. CsA and prednisolone also produced alterations in cytokine expression that favored a shift toward a Th2 response. Pre-treatment with CsA slightly enhanced the efficacy of antiretroviral therapy but did not enhance clearance of FIV. Results highlight the potential for drug-induced perturbation of FIV infection and underscore the need for more information regarding immunopathologic consequences of therapeutic agents on concurrent viral infections.

Episcleral cyclosporine A implants for the management of unilateral keratoconjunctivitis sicca in an 8-year-old mare

An 8-year-old mare was presented for investigation of a 1-month history of blepharospasm, eyelid swelling, corneal edema, and ocular discharge of the right eye (OD). Ophthalmic examination confirmed mucopurulent ocular discharge, conjunctival hyperemia, and a dry, dull appearance to the cornea OD. Schirmer tear test results confirmed an absence of tear production OD (0 mm/min) consistent with keratoconjunctivitis sicca. Treatment with topical 0.2% cyclosporine A resulted in an improvement in clinical signs. An episcleral cyclosporine A implant was placed under standing sedation 5 days after initial presentation. Re-examination 9 days post-operatively confirmed that the mare's tear production in the right eye had improved and no further clinical signs had been observed. Topical medications were gradually discontinued. Re-examinations performed up to 12 months postsurgery showed no recurrence of clinical signs and no adverse effects of the implant. To our knowledge, this is the first report of the use of a cyclosporine A implant in the management of KCS in a horse and highlights its potential as an effective, alternative therapy in the management of KCS in horses.

Immune-mediated keratoconjunctivitis sicca in dogs: current perspectives on management

Keratoconjunctivitis sicca (KCS) is a frequent canine ophthalmic disease, resulting from the deficiency of one or more elements in the precorneal tear film. There are different known causes of KCS in dogs, including congenital, metabolic, infectious, drug induced, neurogenic, radiation, iatrogenic, idiopathic, and immune mediated, though the last one is the most prevalent form in dogs. Initially, clinical signs of KCS include blepharospasm caused by ocular pain, mucoid to mucopurulent ocular discharge, and conjunctival hyperemia; secondary bacterial infection may also occur, with chronicity, corneal epithelial hyperplasia, pigmentation, neovascularization, and corneal ulceration. The diagnosis of KCS is based on the presence of consistent clinical signs and measurement of decreased aqueous tear production using the Schirmer tear test. Therapy is based on administering the following topical drugs: ocular lubricant, mucolytics, antibiotics, corticosteroids, pilocarpine, and immunomodulators. These last drugs (eg, cyclosporine, pimecrolimus, and tacrolimus) have immunosuppressive activity and stimulate tear production. Furthermore, the nerve growth factor is a new subject matter of the research. Although these therapies are advantageous, stimulation of natural tear production seems to provide the highest recovery in clinical signs and prevention of vision loss. The goal of the following article is to describe the recent developments about KCS in dogs emphasizing the use of new therapies.

Equine recurrent uveitis: Human and equine perspectives

Equine recurrent uveitis (ERU) is a spontaneous disease characterised by repeated episodes of intraocular inflammation. The epidemiology of ERU has not been fully elucidated, but the condition appears to be much more common in horses than is recurrent uveitis in humans, especially in certain breeds and geographical regions. Both humans and horses show a similarly altered immune response and a marked autoimmune response as the primary disease pathophysiology. However, an inciting cause is not always clear. Potential inciting factors in horses include microbial agents such as Leptospira spp. Microbial factors and genetic predisposition to the disease may provide clues as to why the horse appears so susceptible to this disease. The aim of this review is to discuss the immunology and genetics of ERU, compare the disease in horses with autoimmune anterior uveitis in humans, and discuss potential reasons for the increased prevalence in the horse.

Canine keratoconjunctivitis sicca: disease trends in a review of 229 cases

OBJECTIVES

To investigate the disease patterns in dogs with keratoconjunctivitis sicca referred to the University of Glasgow Small Animal Hospital.

METHODS

A retrospective study of 229 cases was carried out.

RESULTS

There were 44 breeds in the study, with four breeds, English cocker spaniels, cavalier King Charles spaniels, West Highland white terriers and shih-tzus, making up 58 per cent of the cases. Among these four breeds, two breed-dependent disease patterns, one chronic and one acute, were identified. English cocker spaniels and West Highland white terriers had a mean age at onset of clinical signs of five years and one month and five years and six months, respectively, with more females affected than males. Clinical signs consisted predominantly of conjunctival hyperaemia and mucopurulent discharge, with a relatively low incidence of ulcerative keratitis. In contrast, cavalier King Charles spaniels and shih-tzus showed a more acute disease pattern with a biphasic age distribution at 0 to less than two years of age, and four to less than six and six to less than eight years of age, respectively, with more males affected than females and a significantly higher incidence of ulcerative keratitis in some cases resulting in corneal perforation.

CLINICAL SIGNIFICANCE

The study reveals interbreed differences with respect to sex, age and risk of ulcerative keratitis which have not been detailed previously in a referral population.

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.

Ciclosporin treatment of suspected granulomatous meningoencephalomyelitis in three dogs

Granulomatous meningoencephalomyelitis is an idiopathic disease of the central nervous system of presumed dysimmune origin. This disorder is characterised histologically by an angiocentric inflammatory reaction involving the brain, the spinal cord, and/or the leptomeninges. To date, the standard treatment for granulomatous meningoencephalomyelitis consists of immunosuppressive dosages of glucocorticoids. Ciclosporin A, a potent immunosuppressive agent that blocks the transcription of cytokine genes in activated T cells, has been proposed as a therapeutic alternative. In the present study of three dogs with suspected granulomatous meningoencephalomyelitis, microemulsified ciclosporin, at a dose of 10 mg/kg once daily for at least six weeks, then reducing to 5 mg/kg daily, was administered after a variable period of glucocorticoid treatment, and resulted in a complete resolution of clinical signs. Satisfactory improvement of clinical signs after ciclosporin administration took more time than after glucocorticoid administration. Six weeks after the beginning of ciclosporin treatment, clinical results were similar to those obtained with prednisolone. Adverse effects were minimal with ciclosporin, with only intermittent vomiting.

Immunomodulating agents

Inflammation involves a universally recognized, although incompletely understood, cascade of molecular events orchestrated by lymphokines and other innate biochemicals of immunity. Repeated or extended contact with immunogenic agents results in adaptive immunity involving antigen-induced events that stimulate down-stream immune cells and result in expansion of the inflammatory cascade. When immunogenic stimulation persists or autoregulatory immune mechanisms go awry, however, adaptive immunologic events can result in immune-mediated processes detrimental to systemic or organ-specific homeostasis. Because of the complexities of immunologic events, the potential side effects of long-term corticosteroid therapy, and the focused spectrum of most conventional nonsteroidal anti-inflammatory agents (centered on arachidonic acid-related mechanisms), a variety of other chemotherapeutic immunosuppressive agents have assumed an increasingly prominent therapeutic role in veterinary ophthalmology in the management of chronic ocular inflammatory diseases. In addition, nonimmunosuppressive immunomodulating agents (ie, immuno-stimulants or immunorestoratives) may be used as adjunctive therapies in the management of ocular or visual system diseases.