Abstract
Purpose :
Vernal keratoconjunctivitis (VKC) is a recurrent bilateral chronic ocular allergic inflammatory disease with a not completely identified pathogenic mechanisms. The aim of the study is to identify differences in gene expression between VKC and normal subjects (CT), and to correlate the severity of the disease with particular pathways of gene activation.
Methods :
Cells from conjunctival imprints from active VKC patients (n=15) and normal subjects (CT; n=3) were collected and their RNA isolated with Qiagen RNeasy Mini kit. 10 ng of RNA were processed with GeneChip Pico Reagent kit prior to a 9-cylcle PCR amplification and reverse transcription. Final cDNA were analyzed with Affymetrix Clarion S arrays system. Differential expression (DE) analysis included comparisons between VKC, VKC-subgroups and CT. Regression analysis based on three clinical scores (Score, Oxford and CLECK-VKC) was performed to identify genes associates with disease severity. Enrichment analyses on DE genes (adjusted p <0.05 and absolute log2 fold change >1) and regression analysis genes (p value<0.05) was performed using Gene Ontology (GO) and Reactome.
Results :
Considering the differential expression analysis between VKC and CT, 325 genes significantly differently expressed (DEGs). Different VKC phenotypes had relatively few DEGs in common. An increased number of DEGs was correlated with the severity of the clinical scores. Gene Ontology showed that in limbal VKC the ribonucleoprotein complex biogenesis GO was the most overexpressed while in tarsal VKC several GO were related to the regulation of tissue remodeling. Several GO related to leukocyte activation and mediated immunity were associated to the severity of the Oxford score. 128 out of 226 identifiers in the sample were found in Reactome analysis, where 563 pathways were hit by at least one of them.
Conclusions :
Successful transcriptome-wide expression analysis was performed. Factors involved in both innate and adaptive arms of the immune system were found over-expressed in VKC samples. Different phenotypes and severities of VKC reveal significant and different gene expression trends that may be targeted to improve ocular allergy treatment. While the present transcriptome analysis used a limited number of subjects, our study highlights the complexity of the disease and suggest new area of research to better understand VKC pathophysiology.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.