Evaluation of human conjunctival epithelium by a combination of brush cytology and flow cytometry: an approach to the quantitative technique

Comparison of the use of a standard cytology brush versus a mini cytology brush to obtain conjunctival samples for cytologic examination in healthy dogs

OBJECTIVE

To compare the quality of conjunctival samples for cytologic examination obtained with 2 conjunctival exfoliative brushes, a mini cytology brush (MCB) and a standard cytology brush (SCB), in healthy dogs.

ANIMALS

20 client-owned dogs that were free of ocular disease.

PROCEDURES

A prospective single-center randomized trial was performed. For each dog, conjunctival samples of the right eye were obtained with the 2 brushes (ie, SCB or MCB) at 2 time points that were 5 to 11 days apart. The left eye was used as a control. Cytologic quality of conjunctival samples was scored on the basis of cellularity, clearness of background, uniformity of distribution of cells on the cytology slide, artifacts, cellular overlapping, cell preservation, presence of mucus on the cytology slide, and number of RBCs.

RESULTS

On cytologic evaluation, conjunctival samples collected with an SCB scored significantly better in terms of higher cellularity, less background debris, and more uniformity in the distribution of cells, compared with conjunctival samples collected with an MCB. Conjunctival samples collected with an MCB scored significantly better in terms of less cellular overlapping and less mucus in the background, compared with conjunctival samples collected with an SCB.

CONCLUSIONS AND CLINICAL RELEVANCE

Overall conjunctival samples obtained with an SCB for cytologic evaluation had better diagnostic quality, compared with conjunctival samples obtained with an MCB. Use of an MCB, however, was advantageous to access localized conjunctival areas as well as collect conjunctival samples from patients with small palpebral fissures.

Comparison of 3 corneal cytology collection methods for evaluating equine ulcerative keratitis: Cytobrush, kimura platinum spatula, and handle edge of scalpel blade

PURPOSE

To compare corneal cytology samples from three common sampling techniques: cytobrush (CB), Kimura platinum spatula (KS), and the handle edge of a scalpel blade (SB).

METHODS

Equine patients presenting to the University of Florida College of Veterinary Medicine with ulcerative keratitis were included. Following diagnosis of corneal ulcer and sampling for microbial culture, two cytology samples per technique were collected with sterile CB, KS, and SB in a randomized order. Cytologic evaluation was performed by two observers masked to collection method. Objective measures of sample cellularity, quality, distribution, and identification of infectious organisms were recorded per 10 monolayer cell populations using 50× magnification with oil immersion which were compared to culture results. Variables were compared using ANOVA with Student's t test when appropriate and Cohen's kappa (k) to evaluate inter- and intra-observer agreement (IOA) between observers and techniques.

RESULTS

Twenty equine patients (120 samples) were included. The IOA between observers was substantial (k = 0.75 ± 0.06) for cytological parameters. SB provided the most cellular samples (P < .01). There was a trend toward agreement (k = 0.12 ± 0.16) in technique for sample quality (P = .08). CB and SB had significantly poorer cell distribution than KS (P < .05). Infection was confirmed in 12 of 20 patients with SB and CB techniques having a significantly higher diagnostic yield than KS (P < .05) and was most consistent with infection confirmed on culture.

CONCLUSIONS

The SB provided the most diagnostic samples but all three techniques are clinically useful in evaluating equine ulcerative keratitis.

Dynamic change in natural killer cell type in the human ocular mucosa in situ as means of immune evasion by adenovirus infection

The most severe form of virus-induced inflammation at the ocular surface is epidemic keratoconjunctivitis (EKC), often caused by group D human adenoviruses (HAdVs). We investigated the dynamics and mechanisms of changes in natural killer (NK) cell types in the human ocular mucosal surface in situ over the course of infection. In the acute phase of infection, the mature CD56(dim)NK cells that comprise a major subpopulation in the normal human conjunctiva are replaced by CD56(bright)NK cells recruited to the ocular surface by chemokines produced by the infected epithelium, and NKG2A-expressing CD56(dim) and CD56(bright) NK cells become the major subpopulations in severe inflammation. These NK cells attracted to the mucosal surface are however incapable of mounting a strong antiviral response because of upregulation of the inhibitory ligand human leukocyte antigen-E (HLA-E) on infected epithelium. Furthermore, group D HAdVs downregulate ligands for activating NK cell receptors, thus rendering even the mature NKG2A(-)NK cells unresponsive, an immune-escape mechanism distinct from other adenoviruses. Our findings imply that the EKC-causing group D HAdVs utilize these multiple pathways to inhibit antiviral NK cell responses in the initial stages of the infection.

Diagnostic procedures and management of dry eye

Dry eye disease or dysfunctional tear syndrome is among the most frequent diagnoses in ophthalmology. It is a multifactorial disease of the ocular surface and tear film which results in ocular discomfort, visual disturbances, and tear instability with potential damage to the cornea and conjunctiva. Risk factors for dry eye syndrome include age, sex (female gender), race, contact lens wear, environment with low humidity, systemic medications, and autoimmune disorders. The aim of this paper is to present the systematic classification, epidemiology, diagnostic procedures, and advances in the management of dry eye disease. The recent improvements in comprehending the underlying etiologic factors will inevitably improve future classifications and diagnostic abilities leading to more effective therapeutic options. Treatment of this highly prevalent condition can drastically improve the quality of life of individuals and prevent damage to the ocular surface.

Avaliação da técnica de esfoliação com escova citológica para coleta de células conjuntivais em gatos sadios: comparação entre a face palpebral da membrana nictitante e a conjuntiva palpebral

A citologia conjuntival é um importante meio de diagnóstico de afecções da superfície ocular. Buscam-se técnicas que forneçam quantidade e qualidade celular, com uso de instrumentos que provoquem mínimo trauma e que diminuam as chances de danos iatrogênicos ao olho. Existem diversas técnicas de coleta de células, entre elas encontram-se: impressão, esfoliação e punção por agulha fina. Dentre os métodos utilizados para esfoliação, o uso da escova citológica fornece resultados superiores em vários parâmetros, incluindo a qualidade das células. Estudou-se a citologia conjuntival por esfoliação com escova citológica, utilizada para coleta de material da cérvix uterina, tendo como objetivos determinar se tal instrumento se adequaria à coleta de material da face palpebral da membrana nictitante e da conjuntiva palpebral de felinos sadios. Foram avaliados os seguintes parâmetros: facilidade de execução da técnica, possibilidade de ocorrência de danos iatrogênicos e quantidade e qualidade de células coletadas. Cinquenta gatos machos (58%) e fêmeas (42%), com ou sem raça definida, participaram do estudo. Apenas gatos isentos de alterações oculares no exame físico foram incluídos. A escova citológica se mostrou um instrumento de fácil utilização, que fornece células em quantidade satisfatória e com morfologia preservada. Comparada a conjuntiva palpebral, a face palpebral da membrana nictitante se mostrou um local mais adequado à realização da coleta de amostras citológicas, pela maior facilidade de execução da técnica e menor possibilidade de danos iatrogênicos. No que diz respeito à quantidade e qualidade celular, não houve diferença significativa entre os dois locais de coleta. Foi possível observar células provenientes das diferentes camadas do epitélio conjuntival com predomínio de células intermediárias e ausência de células caliciformes.

Evaluation of dry eye

Dry eye is a common yet complex condition. Intrinsic and extrinsic factors can cause dysfunction of the lids, lacrimal glands, meibomian glands, ocular surface cells, or neural network. These problems would ultimately be expressed at the tear film-ocular surface interface. The manifestations of these problems are experienced as symptoms such as grittiness, discomfort, burning sensation, hyperemia, and secondary epiphora in some cases. Accurate investigation of dry eye is crucial to correct management of the condition. Techniques can be classed according to their investigation of tear production, tear stability, and surface damage (including histological tests). The application, validity, reliability, compatibility, protocols, and indications for these are important. The use of a diagnostic algorithm may lead to more accurate diagnosis and management. The lack of correlation between signs and symptoms seems to favor tear film osmolarity, an objective biomarker, as the best current clue to correct diagnosis.

Topographical distribution and characterization of epithelial cells and intraepithelial lymphocytes in the human ocular mucosa

The conjunctiva plays a key role in the protection of the ocular surface by initiating and regulating immune responses. In this study, we analyze the relative proportion of intraepithelial lymphocytes (IELs), apoptotic cells, and proliferative state in three different topographical regions of the normal human conjunctiva. Superior tarsal, superior bulbar, and inferior tarsal-bulbar-fornical conjunctival cells were collected by brush cytology from 63 healthy donors. Flow cytometry analysis showed higher levels of CD3⁺ and CD8⁺ IELs in both upper tarsal and bulbar conjunctiva than in the inferior tarsal-bulbar-fornix, where the CD19⁺ B cells were increased. For all zones two different cell populations (by cell size and complexity) were present in the apoptosis assay. The more complex cells were reduced within the inferior tarsal-bulbar-fornix when compared with the superior bulbar and tarsal areas. Less complex cells were more predominant in the inferior conjunctiva and were mainly alive. The mean proliferation index of the conjunctival epithelium was significantly lower in the superior bulbar conjunctiva than in superior tarsal and inferior fornical conjunctivas. These findings suggest that each topographical zone from normal human conjunctiva has a unique profile of immunophenotype, viability, and proliferative state that could be related to a differentiated regional functionality.

A novel scraping cytology score system (SCSS) grades inflammation in dry eye patients

PURPOSE

We propose a conjunctival Scraping Cytology Scoring System (SCSS) as a reliable method to diagnose and score ocular surface inflammation in dry eye.

METHODS

Twenty normal subjects and 46 patients with dry eye of various severities were included in the study. Clinical signs were scored 1-4; an Ocular Surface Disease Index (OSDI) questionnaire was used to grade subjective symptoms. Concentrations of serum albumin and interleukin-6 (IL-6) in tears were evaluated. Scraped conjunctival cytology samples were processed and examined with light microscopy. The number of inflammatory cells was staged and sub-scores were assigned. SCSS resulted from their sum and ranged from 0-12. Statistical evaluation was performed by applying the unpaired Student's t-test and the Spearman's correlation test (significance p < 0.05). SCSS was also analyzed for sensitivity, specificity, ROC curves, likelihood ratio LR+, positive (PPV) predictive value.

RESULTS

SCSS was positively correlated to clinical sign score, OSDI score, exudated serum albumin, and IL-6 in either control (Spearman's correlation test always p < 0.05) and in dry eye patients (respectively, p < 0.0001, p < 0.01, p < 0.05, and p < 0.0001). SCSS >or= 4 was selected as the cut-off value for moderate dry eye (LR+ 10,9; PPV 22,5), SCSS >or= 9 was selected as the cut-off value for severe dry eye (LR+ 15,6; PPV 26,2).

CONCLUSIONS

SCSS can be applied in any trained laboratory. It is correlated with clinical signs and symptoms, and it shows a diagnostic performance to grade inflammation in dry eye, comparable to more expensive cytokine assay.

[Ocular surface investigations in dry eye]

Dry eye is a complex clinicopathological entity involving tear film, lacrimal glands, eyelids, and a wide spectrum of ocular surface cells, including epithelial, inflammatory, immune, and goblet cells. From the tightly regulated lacrimal film functions and structure, a large variety of investigations have been developed, including tear meniscus measurements, fluorophotometry, meibometry, interference pattern analysis, evaporation rate, tear osmolarity, and thermography. Dry eye conditions also interfere with the ocular surface, causing corneal irregularities that may be explored using the techniques of videokeratography and in vivo confocal microscopy, or optical impairment, as confirmed by aberrometry. At the level of ocular surface cells, impression cytology remains a standard for assessing cell alterations. It has greatly benefited from new confocal microscopy, molecular biology, and flow cytometry techniques. Biological assessment of tear proteins or other mediators is also useful. Major limits should be acknowledged, however, such as technical issues in tear film collection, especially in dry eyes, and the lack of standardization of most measurements. Tear osmolarity, electrophoresis, and dosage of normal tear proteins, such as lysozyme or lactoferrin, remain the most useful tests. Finally, some extraocular explorations such as accessory gland biopsy or serum antinuclear antibody dosage may be useful for assessing the diagnosis of Sjögren's syndrome.

Conjunctival impression cytology in dogs

OBJECTIVE

Ocular conjunctivas of healthy dogs were studied by conjunctival impression cytology for evaluation of feasibility, protocol standardization, and normal cytologic pattern recognition of this technique.

ANIMALS STUDIED

Twenty healthy, adult, cross-breed dogs.

PROCEDURES

Samples of the bulbar conjunctiva were collected after instillation of topical anesthetic drops at the ocular surface. Impression cytology was performed by applying asymmetric strips of Millipore filter on the superior temporal bulbar conjunctiva near the limbus. The filter strip was gently pressed against the conjunctiva for 5 s and removed with a peeling motion. Samples were immediately fixed in 95% ethyl alcohol, stained with periodic acid-Schiff and hematoxylin, and mounted on slides cover-slipped using synthetic resin. The slides were examined by light microscopy.

RESULTS

Microscopic examination of the impressions revealed superficial, intermediate and basal epithelial cells arranged in sheets. Keratinized epithelial cells, goblet cells and leukocytes, as well as cellular debris and mucus were observed.

CONCLUSIONS

Feasibility of impression cytology for sampling the bulbar conjunctiva of the dog and the standardization the the proposed protocol was shown. The results allowed the recognition the the normal cytologic pattern of healthy conjunctivas in dogs.

Laboratory findings in tear fluid analysis

The tear film, composed of the lipid, aqueous and mucin layers, has many functions including defending the ocular surface. The tear film covering the ocular surface presents a mechanical and antimicrobial barrier and ensures an optical refractive surface. The lipid component originates from the meibomian glands of the tarsus and forms the superficial layer of the tear film. The aqueous component contains electrolytes, water, and a large variety of proteins, peptides and glycoproteins, and is primarily secreted by the lacrimal gland. Mucins are glycoproteins expressed by epithelial tissues of mucous surfaces. They protect tissues by functioning as antioxidants, providing lubrication, and inhibiting bacterial adherence. Quantitatively and qualitatively, its composition must be maintained within the fairly narrow limits to maintain a healthy and functional visual system. Abnormalities of the tear film, affecting the constituents or the volume, can rapidly result in serious dysfunction of the eyelids and conjunctiva and ultimately affect the transparency of the cornea. Many ocular surface tests have been developed for the clinical diagnosis of dry eye syndromes. This paper provides an overview on laboratory methods for the analysis of the tear film. Understanding the components of the tear film will aid in the treatment of dry eye syndromes and the ocular surface diseases.

Flow cytometry in conjunctival impression cytology: a new tool for exploring ocular surface pathologies

Flow cytometry (FCM) is a widely used technique, not only in immunology and hematology but also in many other domains and new applications have been developed in ophthalmology, for investigating ocular surface biology and pathophysiology. Apoptosis, proteins specific of cell lineage, expression of activation or immune-related markers, proinflammatory cytokine production, multi-drug resistance and oxidative stress are some examples of possible pathways that may be explored directly using ocular surface cells removed with the non-invasive technique of impression cytology, by means of flow cytometry. Conjunctival cells are thus collected by impression cytology on a filter, fixed in paraformaldehyde and dissociated by agitation before immunostaining and FCM processing. Important observations have been made concerning Sjögren's syndrome, ocular allergy and antiglaucoma eye drop toxicity. Studies performed on impression cytology with FCM techniques confirmed inflammatory and apoptotic patterns in a large number of patients with keratoconjunctivitis sicca or receiving long-term treatments with antiglaucoma drugs, even though they did not present any clinical signs of inflammation. FCM may now be used for large multicenter clinical trials and has already contributed to a better understanding of ocular surface pathophysiology, the monitoring of new immunomodulating drugs and knowledge concerning topical drugs, as regards both efficacy and safety.