Dataset Information

Corneal Changes in Acanthamoeba Keratitis at Various Levels of Severity: An In Vivo Confocal Microscopic Study.

ABSTRACT:

Purpose

To investigate the relationship between Acanthamoeba cysts and inflammatory cells in Acanthamoeba keratitis (AK) by in vivo confocal microscopy (IVCM).

Methods

A case-control study included 30 patients with AK and 20 normal controls. The severity of the AK was divided into mild, moderate, and severe. The central cornea and four standard quadrants of the peripheral cornea were imaged by IVCM. The cyst infiltration and dendritic cell (DC) density and maturity (size, length, field, and number of dendrites) were quantified. The relationship between clinical severity, cyst density, and DC alterations was characterized by Spearman correlation analysis.

Results

The maximum cyst density in the mild, moderate, and severe groups was 31.3 cysts/mm2 (17.2-32.8), 62.5 cysts/mm2 (59.3-103.1), and 162.5 cysts/mm2 (65.6-215.6), respectively. Compared to normal participants, a significant increase in the mean corneal DC density was detected in patients with AK (290.2 ± 97.0 vs. 25.3 ± 8.3 cells/mm2; P < 0.001). Patients with AK presented an increase in median DC size (178.3 vs. 63.6 µm2/cell, P < 0.001), median DC field (518.1 vs. 256.6 µm2/cell, P = 0.008), and median DC dendrite length (42.3 vs. 14.7 µm/cell, P < 0.001). Increased AK severity was correlated with an increase in cyst density, DC size, and dendrite length (all P < 0.05). An increase in cyst density was significantly correlated with an increase in DC density (β = 0.484, P = 0.026) and DC size (β = 0.557, P = 0.009).

Conclusions

Cyst density and depth of infiltration as well as maturity of the surrounding DC increased significantly with the severity of AK.

Translational relevance

Quantitative analysis of cyst density and DC maturity may provide a new method of evaluating the severity of AK.

SUBMITTER: Wei Z

PROVIDER: S-EPMC8196423 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundAcanthamoeba spp. are the causative agents of a severe keratitis occurring mainly in contact lens wearers. The genus comprises more than 24 species that are currently divided into 20 different genotypes (T1-T20) according to sequence variations in the 18S rRNA gene. The objective of this study was to identify the genotypes and sub-genotypes of Acanthamoeba isolates collected at the Parasitology Laboratory of the Public Health Institute of Chile, the only laboratory in the country where Acanthamoeba screening is performed. This is the first report of genotypic identification of clinical isolates of Acanthamoeba in Chile and one of the few in South America.ResultsIn this study, 114 Acanthamoeba isolates from 76 Acanthamoeba keratitis patients, obtained between 2005-2016, were genotyped. T4 was the predominant genotype; T2 and T11 genotypes, which are scarcely reported worldwide, were also identified in Chilean patients (one and two patients, respectively). This is the first report of T2 and T11 genotypes isolated from Acanthamoeba keratitis patients in South America. It is also the first report of the T2 genotype circulating in this continent. Analysis of the diagnostic fragment 3 region of the 18S rRNA gene showed 24 T4 variants, with a predominance of the sub-genotype T4/A, followed by T4/B, T4/G, T4/C and T4/D. Bayesian analysis revealed three groups among the T4 variants: two well supported groups that included 12 and 7 sub-genotypes, respectively, and a weakly supported group that included 5 sub-genotypes. Most of the predominant T4 sub-genotypes belonged to the same group, which included 71.3% of the patients, while some minority variants lied mainly in the other two clusters.ConclusionsT2, T4 and T11 genotypes were predominantly isolated from the Acanthamoeba keratitis patients in Chile. Chilean predominant T4 sub-genotypes, which have also been reported worldwide, formed a separate cluster of the minority T4 variants. This study provides useful information about the predominant genotypes and subgenotypes that would be useful in selecting suitable strains to develop immunological and/or molecular diagnostic assays in Chile.