Update on the role of impression cytology in ocular surface disease

Evaluation of Dry Eye Severity and Ocular Surface Inflammation in Patients with Autoimmune Rheumatic Diseases

PURPOSE

To evaluate dry eye severity and ocular surface inflammation in autoimmune rheumatic diseases (ARDs).

METHODS

Seventy-nine patients with ARDs were enrolled, including 26 patients with rheumatoid arthritis (RA), 33 patients with systemic lupus erythematosus (SLE), and 20 patients with primary Sjögren's syndrome (pSS). All patients underwent ocular surface evaluations, including ocular surface symptoms, signs, conjunctival impression cytology, and tear multicytokine detection. Systemic conditions, including disease duration, disease activity, and serological parameters, were also noted.

RESULTS

SLE patients had the shortest disease duration, and nearly half of them had low disease activity, while RA patients and pSS patients had a relatively long disease duration, and approximately 90% of them had moderate or high disease activity. The incidence of dry eye and the levels of the proinflammatory tear cytokines in SLE were significantly lower than those in RA and pSS. However, ocular surface squamous metaplasia was more severe in SLE and pSS than in RA. Dry eye severity in all ARD patients was shown to be independent of disease activity, while Nelson's grades were positively correlated with disease duration in RA patients. Disease-related serological parameters were associated with tear proinflammatory cytokines in all ARD patients.

CONCLUSIONS

Variable degrees of dry eye and immune-mediated ocular surface inflammation persist in different ARD patients. In addition to a well-known association between dry eye and pSS, dry eye is also commonly observed in SLE and RA patients. Therefore, there is a definite need for regular ophthalmologic evaluations and topical medications in all patients with ARDs.

Non-invasive harvesting of conjunctival cells for whole transcriptome sequencing

The purpose of this study was to determine the feasibility of using a non-invasive technique, the EYEPRIM™ conjunctival cell impression device, to harvest sufficient RNA from conjunctival cells for the whole-transcriptome sequencing. Conjunctival cells from 40 participants were collected using an EYEPRIM™ conjunctival cell impression device. RNA was extracted from the samples, followed by library construction and transcriptome sequencing. Quality checks were performed for each technical step of the experiment, and the feasibility of this procedure was examined. RNA of sufficient yield and quality was successfully extracted following additional disruption and homogenization of the conjunctival cells and collection of two impression samples per eye. Successful library preparation and RNA sequencing were performed, with all 40 samples passing the various quality checks used for each step. In conclusion, harvesting cells from the ocular surface using an impression cytology device yields good quality and sufficient mRNA for whole transcriptome sequencing to study diseases of the eye. This technique provides a convenient alternative to using post-mortem tissues or surgical excisions.

Ocular surface involvement and histopathologic changes in the acute stage of Stevens-Johnson syndrome and toxic epidermal necrolysis: a cross-sectional study

BACKGROUND

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare and extremely serious drug-induced dermatological disorders. The ocular surface condition at the early stage has been little studied and should contribute to novel perspectives in early and effective topical therapy of these diseases. The objectives of the study were to evaluate the acute phase of ocular surface involvement and histopathologic changes in patients with acute SJS/TEN.

METHODS

Ten patients with acute phase of SJS/TEN onset and eleven age- and sex-matched healthy volunteers were recruited. Ocular surface symptoms and signs, conjunctival impression cytology, and tear multi-cytokine were assessed.

RESULTS

Ocular surface objective signs were normal at the acute stage of SJS/TEN, while most patients have abnormal ocular surface subjective symptoms and meibomian gland secretion. Conjunctival impression cytology showed a significant decrease in goblet cell density and severe ocular surface squamous metaplasia in acute SJS/TEN patients. Tear multi-cytokine analysis showed all 21 pro- and anti-inflammatory cytokines all sharply elevated. Goblet cell density was significantly negatively correlated with tear C-X3-C motif chemokine ligand 1 (CX3CL1) and interleukin 13.

CONCLUSIONS

Severe pathologic squamous metaplasia and inflammation onset in the ocular surface at the acute stage of the SJS/TEN, even if the ocular surface condition seemed basically normal with adequate systemic immunosuppressant and general supportive treatment. Early topical anti-inflammatory therapy should be carried out actively.

Automated identification and quantification of activated dendritic cells in central cornea using artificial intelligence

PURPOSE

To validate an algorithm quantifying activated dendritic cells (aDCs) using in-vivo confocal microscopy (IVCM) images.

METHODS

IVCM images obtained at the Miami Veterans Affairs Hospital were retrospectively analyzed. ADCs were quantified both with an automated algorithm and manually. Intra-class-correlation (ICC) and a Bland-Altman plot were used to compare automated and manual counts. As a secondary analysis, individuals were grouped by Dry Eye (DE) subtype: 1) aqueous-tear deficiency (ATD; Schirmer's test ≤5 mm); 2) evaporative DE (EDE; TBUT≤5s); or 3) control (Schirmer's test>5 mm; TBUT>5s) and ICCs were re-examined.

RESULTS

173 non-overlapping images from 86 individuals were included in this study. The mean age was 55.2 ± 16.7 years; 77.9% were male; 20 had ATD; 18 EDE and 37 were controls. The mean number of aDCs in the central cornea quantified automatically was 0.83 ± 1.33 cells/image and manually was 1.03 ± 1.65 cells/image. A total of 143 aDCs were identified by the automated algorithm and 178 aDCs were identified manually. While a Bland-Altman plot indicated a small difference between the two methods (0.19, p < 0.01), the ICC of 0.80 (p = 0.01) demonstrated excellent agreement. Secondarily, similar results were found by DE type with an ICC of 0.75 (p = 0.01) for the ATD group, 0.80 (p = 0.01) for EDE, and 0.82 (p = 0.01) for controls.

CONCLUSIONS

Quantification of aDCs within the central cornea may be successfully estimated using an automated machine learning based algorithm. While this study suggests that analysis using artificial intelligence has comparable results with manual quantification, further longitudinal research to validate our findings in more diverse populations may be warranted.

Cytological and microbiological evaluation of conjunctiva in camels with and without conjunctivitis

OBJECTIVE

To describe the cytological analysis of conjunctiva from normal camels and camels with bacterial conjunctivitis.

ANIMALS STUDIED

This study was conducted on 7 normal camels and 15 camels affected with conjunctivitis. The affected camels had a history of conjunctivitis with signs including chemosis, blepharospasm, frequent blinking, and mild-to-moderate serous, mucoid, or purulent ocular discharge.

PROCEDURES

Bacterial swabs were collected from the inferior conjunctival sac of the affected eye without topical anesthetics. Conjunctival smears were obtained from the conjunctival surface for cytological analysis.

RESULTS

The cellular analysis of ocular smears revealed a higher percentage of basal cells, neutrophils, eosinophils, and macrophages in camels with conjunctivitis compared with normal camels. In contrast to this, smears from normal camels showed an increased percentage of superficial epithelial cells compared with affected camels. The microbiological assessment of conjunctival swabs collected from affected animals identified a bacterial growth of Staphylococcus aureus., Bacillus sp., Streptococcus sp., Enterococcus faecium., Staphylococcus sp., Corynebacterium sp., Coryne pseudotuberculosis., Saprophytica, Enterobacter cloacae, Escherichia coli, Proteus mirabilis, Proteus vulagaris, and Pseudomonas aeruginosa.

CONCLUSIONS

It was observed that bacterial conjunctivitis in camels was associated with increased percentages of basal epithelial cells, neutrophils, eosinophils, and macrophages compared with normal camels, while normal camels showed an increased percentage of superficial epithelial cells compared with affected camels.

Protective Role of Bone Marrow Mesenchymal Stem Cells (BMSCs) in Repairing Epithelial Cells of Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the main causes of blindness. By directly employing mesenchymal stem cells to repair damaged retinal tissues, we aim to study the underlying repair mechanisms. 30 DR patients were included, along with 30 healthy control cases. Western-blot and qRT-PCR were conducted to measure PI3K/Akt pathway-related genes. The PI3K/Akt antagonist (Rigosertib) was utilized in the induction process of cell differentiation to analyze the effects of PI3K/Akt pathwayspecific proteins and mRNAs. DR patients showed significantly elevated expression of PI3K/Akt compared to control. With prolongation of induction, the expression of normal epithelial cell-related genes (SpC, SpB, SpA, CK18, KGF and Occludin) was elevated along with upregulated Occludin and KGF, two specific proteins of healthy epithelial cells. Meanwhile, the quantities of Occludin and KGF in cell culture medium showed a gradual downward trend. In the differentiation of BMSCs towards epithelial cells, addition of PI3K/Akt antagonist Rigosertib was negatively correlated with the expression of several genes (IGF-1, shh, EGF, mTOR, AKT and PI3K) and decreased the quantities of PI3K/Akt pathway-specific proteins (mTOR, PI3K and AKT). In conclusion, BMSCs can effectively reduce the release of cytokines in DR and promote the repair of damaged diabetic retina, possibly through regulation of PI3K/Akt signaling pathway.

Quantitation of Pax-6 protein in ocular impression cytology samples using an electrochemiluminescence immunoassay

Paired box protein Pax-6 (oculothrombin) is a transcription factor that plays an important regulatory role in ocular, brain, and pancreatic development. Mutations of the PAX6 gene cause aniridia and Peters anomaly. Reduction in Pax-6 protein is also associated with ocular diseases such as dry eye. An electrochemiluminescence immunoassay method using the Meso Scale Discovery platform was developed to measure Pax-6 protein levels in corneal epithelial cells obtained by impression cytology. Impression cytology involves harvesting ocular epithelial cells by applying a polyethersulfone membrane patch briefly to the ocular surface using a commercially available EYEPRIM™ device. The epithelial cells that adhere to the membrane patch of the EYEPRIM™ device provide a biological sample which can be assayed for Pax-6 protein levels. Assay development identified an antibody pair capable of detecting purified recombinant Pax-6 protein produced in mammalian cells. The optimized assay has a dynamic range of 24 pg mL^-1 to 100,000 pg mL^-1 and a lower limit of quantification of 24 pg mL^-1. Assay selectivity was demonstrated using either HeLa or HEK293 cells transfected with inhibitory RNA. Finally, the method was validated by measuring Pax-6 protein levels in impression cytology acquired samples obtained using the EYEPRIM™ device from rabbit cornea.

Regulation of Autophagy and Inflammation Improves the Corneal Injury in the Model of Rats with Xerophthalmia

This study assessed the mechanism of regulation of autophagy and inflammation on corneal injury in the model of rats with xerophthalmia. The level of inducer and inhibitor of autophagy in the model of rats with xerophthalmia was detected and cell proliferation was evaluated by MTT assay together with analysis of colony formation, cell apoptosis and cycle by FCM. The effect of inducer on the corneal injury and inflammation was assessed. The level of autophagy marker LC3 was elevated significantly after treatment with autophagy inducer along with increased cell proliferation and migration and strengthened sensibility of corneal epithelial cells on corneal injury and inflammation and autophagy rate. In addition, cells in the established model was blocked at G2/M phase. Moreover, autophagy inducer significantly upregulated MMP-10 expression. Furthermore, there was a target relationship between LC3 and P62. In conclusion, the cell migration, growth and autophagy is induced with autophagy inducer in the model of rats with xerophthalmia, indicating that autophagy inducer might be a brand-new therapeutic target spot for the treatment of xerophthalmia.

Bone Marrow Mesenchymal Stem Cells (BMSCs)-Derived Exosomes Promotes Proliferation and Differentiation of Retinal Neuron-Like Cells to Repair Corneal Epithelial Damage

Dry eye disease (DED) is a common ocular surface disease. Bone marrow mesenchymal stem cells (BMSCs) can differentiate into various cells, and BMSC-derived exosomes (BMSC-exo) is essential to maintaining BMSCs stemness. This study aimed to elucidate the mechanism underlying BMSCexo in DED. Sixty rats with corneal epithelial injury were treated with BMSCs or BMSC-exo and untreated (each group, n = 20) followed by analysis of the effect of BMSCs and BMSC-exo by evaluating the corneal epithelium damage via measuring the Basso-Beattie-Bresnahan (BBB) score on 1st, 3rd, 7th, 14th, 28th day after treatments. TUNEL staining assessed cell apoptosis, NF200 expression and the number of BrdU-positive cells. There was no significant difference in BBB scores among three groups on the 1st and 3rd day after treatment (p > 0.05) with significant difference on the 7th, 14th, and 28th day (p <0.05); compared with control group, BMSCs group and combination group had significantly higher BBB score (p < 0.05). The amount of apoptotic cells rose on 3rd and then gradually decreased since 7th day. Moreover, BMSCs and BMSC-exo decreased the apoptotic index and increased absorbance of NF200 and BrdU-positive rate (p < 0.05). BMSC-exo alleviates corneal epithelial damage in DED and facilitates wound healing possibly through reducing cell apoptosis and increasing retinal neuron-like cell proliferation protein.

An Improved Ocular Impression Cytology Method: Quantitative Cell Transfer to Microscope Slides Using a Novel Polymer

PURPOSE

To develop a more efficient impression cytology (IC) method for the transfer of ocular surface cells onto glass microscope slides for cytochemical, immunocytochemical, and immunofluorescence studies.

METHODS

Cells are lifted off the ocular surface with a mixed cellulose ester membrane and then firmly attached to a glass slide using a novel triblock copolymer comprised of collagen type I, polyethylenimine and poly-L-lysine (CPP), and crosslinking cells and glass slide by heating and cooling. The membrane is removed intact after softening it with a butanol/ethanol solution. Transfer of cells is complete in about 10-15 minutes and is ready for staining. The efficiency of our cell transfer method was compared to current methods based on poly-L-lysine and albumin paste.

RESULTS

Our method ensured almost complete transfer of cells. In contrast, the transfer of rabbit conjunctiva cells onto poly-L-lysine-covered slides was 37.5 ± 6.3% lower, and onto albumin-paste covered slides 62.5 ± 5.6% lower (mean ± SD); the transfer of rabbit goblet cells was even less efficient. The new method was also more efficient for transfer of cells from human oral mucosa obtained by IC. Transferred cells were successfully stained with H&E, chemiluminescence, and immunofluorescence agents. Using our method, we stained ocular surface cells for S100A4 and ATF4, both of which play a role in the pathophysiology of dry eye disease. We obtained similar results with oral mucosal cells, suggesting the generalizability of our approach. We propose an explanation for the strong adhesion of cells to the glass slide, which is based on their interactions with the triblock copolymer.

CONCLUSIONS

We developed a novel approach for the efficient and rapid transfer of cells obtained by IC onto glass microscope slides using a novel copolymer. Compared to available methods, our improved approach makes IC robust and simple, and should increase its diagnostic yield and clinical applicability.

Tear Function Alterations and Conjunctival Impression Cytology Findings in Patients With Gout

OBJECTIVES

The aim of this study was to evaluate the tear functions and conjunctival impression cytology (CIC) findings of patients with gout and compare them with healthy controls.

METHODS

Thirty-four patients with gout (group 1) and 32 age-matched and gender-matched healthy individuals (group 2) were included in this cross-sectional study. Schirmer 1 test, tear breakup time (TBUT), Ocular Surface Disease Index (OSDI) score, and CIC grade were evaluated and compared between the groups.

RESULTS

There was no significant difference between the groups in gender and age (P=0.923 and P=0.078, respectively). The mean of Schirmer 1 test result was significantly lower in group 1 (9.74±6.03 mm) than that in group 2 (17.16±9.33 mm) (P<0.001). The TBUT was also significantly lower in group 1 (7.00±2.09 seconds) than that in group 2 (12.75±5.25 seconds) (P<0.001). The OSDI score (20.04±12.92) was significantly higher in group 1 than that in group 2 (6.19±10.07) (P<0.001). Although 10 patients (29.4%) in group 1 had the CIC grade of 2 to 3, none of the controls had CIC grade 2 to 3. The mean CIC grade in group 1 (1.15±0.89) was significantly higher than that in group 2 (0.47±0.51) (P<0.001).

CONCLUSIONS

The results of this study suggest that ocular surface alterations assessed by CIC and tear function abnormalities are more common in patients with gout.

Conjunctival impression cytology and tear film parameters in patients with multiple sclerosis

PURPOSE

To evaluate conjunctival impression cytology (CIC) findings and tear film parameters in patients with multiple sclerosis (MS) compared with controls.

METHODS

Thirty-three patients with MS (MS group) and 33 age- and sex-matched healthy subjects (control group) were included in this cross-sectional comparative study. CIC grades, tear break-up time (TBUT), Schirmer 1 test results, and Ocular Surface Disease Index (OSDI) scores were compared between the two groups, and correlations between CIC grade, TBUT, Schirmer 1 test result, OSDI score, Expanded Disability Status Scale score, and disease duration were analyzed.

RESULTS

Mean CIC grade was higher in the MS group than in the control group (1.48 ± 0.71 and 0.39 ± 0.56, respectively; p < 0.001). In the MS group, CIC of the 14 participants (42.4%) was grade 2-3. In the control group, CIC of the only one participant (3.3%) was grade 2, and none of them was grade 3. TBUT (8.12 ± 3.16, 13.06 ± 4.23 s in MS and control groups, respectively; p < 0.001) and Schirmer 1 test results (8.45 ± 5.75, 17.36 ± 10.89 mm in MS and control groups, respectively; p < 0.001) were lower, and OSDI score (36.36 ± 19.19, 13.70 ± 15.36 in MS and control groups, respectively; p < 0.001) was higher in the MS group compared to the control group.

CONCLUSION

In patients with MS, objective findings of dry eye, subjective symptoms related to dry eye, and CIC abnormalities, including high grades of conjunctival squamous metaplasia and goblet cell loss, are more common. Patients with MS should be monitored for ocular surface alterations and dry eye disease.

Comparing the results of manual and automated quantitative corneal neuroanalysing modules for beginners

This study aimed to evaluate the reliability of in vivo confocal microscopic neuroanalysis by beginners using manual and automated modules. Images of sub-basal corneal nerve plexus (SCNP) from 108 images of 18 healthy participants were analyzed by 7 beginner observers using manual (CCMetrics, [CCM]) and automated (ACCMetrics, [ACCM]) module. SCNP parameters analyzed included corneal nerve fiber density (NFD), corneal nerve branch density (NBD), corneal nerve fiber length (NFL), and tortuosity coefficient (TC). The intra-observer repeatability, inter-observer reliability, inter-module agreement, and left–right eye symmetry level of SCNP parameters were examined. All observers showed good intra-observer repeatability using CCM (intraclass correlation coefficient [ICC] > 0.60 for all), except when measuring TC. Two observers demonstrated especially excellent repeatability in analyzing NFD, NBD, and NFL using manual mode, indicating the quality of interpretation may still be observer-dependent. Among all SCNP parameters, NFL had the best inter-observer reliability (Spearman’s rank-sum correlation coefficient [SpCC] and ICC > 0.85 for the 3 original observers) and left–right symmetry level (SpCC and ICC > 0.60). In the additional analysis of inter-observer reliability using results by all 7 observers, only NFL showed good inter-observer reliability (ICC = 0.79). Compared with CCM measurements, values of ACCM measurements were significantly lower, implying a poor inter-module agreement. Our result suggested that performance of quantitative corneal neuroanalysis by beginners maybe acceptable, with NFL being the most reliable parameter, and automated method cannot fully replace manual work.

Ocular Surface and Conjunctival Cytology Findings in Patients With Confirmed COVID-19

PURPOSE

To assess the effect of severe acute respiratory syndrome coronavirus-2 infection on the conjunctiva and tear film.

METHODS

Thirty-eight patients with confirmed COVID-19 and 31 healthy controls were included in this prospective and observational study. Individuals with COVID-19 formed the patient group, and healthy individuals formed the control group. Conjunctival impression cytology (CIC), TBUT, Schirmer II test, and ocular surface disease index were evaluated in all participants.

RESULTS

No significant difference was observed regarding the mean age and gender between the groups (P=0.786 and P=0.122, respectively). The mean TBUT and Schirmer II test results did not differ between the two groups (P=0.496 and P=0.447, respectively). The CIC results revealed decreased density and cell size of goblet cells and moderate to high enlargement, squamous changes, and increased nucleocytoplasmic ratio in nongoblet epithelial cells in the COVID-19 group compared with the control group. Based on the Nelson classification in CIC samples, 60.6% of the COVID-19 group and 19.4% of the control group had changes consistent with grade 2 or above. The presence of neutrophils in CIC was significantly higher in the COVID-19 group (P<0.001), whereas the presence of lymphocyte was similar between the two groups (P=0.247).

CONCLUSION

This study revealed the pathological conjunctival alterations in patients with COVID-19 and demonstrated that pathological ocular surface alterations may present even at the beginning of COVID-19 without clinically significant ocular manifestation.

Ocular cytology: Diagnostic features and ongoing practices

Ocular cytology specimens are small, with limited options for a repeat biopsy. Appropriate handling of these specimens and triaging for ancillary testing can be taxing. In this article, the author reviews a selection of potentially challenging diagnoses and current common practices and methods used in diagnosing ocular diseases by cytology. The majority of cytology specimens submitted for evaluation of ocular diseases can be divided into 3 major categories: surface epithelial corneal and conjunctival cytology samples, intraocular fluids from the anterior (aqueous fluid) or posterior (vitreous fluid) chambers of the eye, and intraocular fine-needle aspiration specimens. The clinical findings, testing, and cytologic features of ocular surface epithelial infections, inflammations and neoplasia are discussed; and challenges in processing and diagnosing intraocular infections, chronic uveitis, and vitreoretinal lymphoma are reviewed. Novel molecular testing in the cytologic diagnosis and classification of uveal melanoma also is explored. Cytology evaluation of corneal epithelial and stromal cells, anterior chamber and vitreous samples, and fine-needle aspiration biopsies can provide detailed diagnostic findings to aid in the treatment and follow-up of patients with ocular diseases.

Regional Comparison of Goblet Cell Number and Area in Exposed and Covered Dry Eyes and Their Correlation with Tear MUC5AC

To compare goblet cell (GC) number and area in the covered superior (SB) versus exposed temporal (TB) bulbar conjunctiva in control versus aqueous tear deficient eyes (ATD) and evaluate correlation with tear MUC5AC protein. SB and TB impression cytology performed on control eyes, Sjögren syndrome (SS) ATD, and non-SS ATD was stained with period acid Schiff. GC number and area were measured with image analysis software. Protein-normalized MUC5AC level was measured in Schirmer strip-collected tears. Compared to control conjunctiva, GC number and area were significantly lower in SS, non-SS, and combined ATD groups in exposed TB, and were also significantly lower in SS and combined ATD groups in covered SB. In all ATD, GC number and area were significantly correlated, but differences between SB and TB were non-significant. Normalized tear MUC5AC protein was lower in all ATD groups versus control eyes, and correlated only with GC area. GCs are significantly decreased in the covered and exposed conjunctiva in SS. GC area may be a better disease measure than number for ATD. Correlation between tear MUC5AC concentration and GC area suggests tear MUC5AC mucin can be used as a disease-relevant biomarker for conjunctiva GC health.