MEIBOMIAN GLAND DYSFUNCTION (MGD) AND DRY EYE DISEASE (DED). IMPORTANCE OF INFLAMMATION AND GENETIC IN THE DIAGNOSIS AND FOLLOW-UP

To characterize the overexpression of genes related to inflammation in tears of patients with MGD and DED, in order to obtain a genetic signature to facilitates diagnosis and therapeutic strategies.

Department of Ophthalmology and Molecular Biology Lab (Pangaea). Hospital Universitario Dexeus, Universidad Autónoma de Barcelona. Barcelona, Spain.

Prospective single-center study with 60 subjects, 22 control and 38 MGD-DE patients of wich in 11 cases the quality of the sample did not allow obtaining a valid result, while the remaining 27 cases were successfully analyzed by nCounter. Of the 27 patients, the mean age: 63 years, range 27-87, 15 female and the degree of severity: 13 mild, 12 moderate and 2 sever. Tears samples were obtained with micropipeta from de inferior conjunctival fornix and were amplified using the nCounter® Low RNA Input Amplification Kit. The Human Immunology V2 Panel (NanoString Technologies, Seattle, WA), whit 579 transcripts genes were applied. A cross-validation using selected features was performed using random forest (RF), gradient boosting (GB) and K-Nearest Neighbors (KNN) classifiers with three iterations. The model showing highest accuracy was then selected as the final model. Signature scores for each sample were derived from the final model.

We analyzed the differentially expressed genes (DEGs) of transcripts from DED patients and controls and we obtained a total of 45 genes upregulated in the patients group, associated with the 7 inflammatory pathways, including MHC class I and II antigen presentation complex or Type I interferon signaling. Form the 45 genes, the RFE algorithm selected a predictive gene signature with 4 genes and was able to classify MGD-DE patients and controls and providing a ROC AUC of 0.86. The 4 genes chosen were IFITM1, HLA-A, Cathepsin S (CTSS) and C-C Motif Chemokine Ligand 4 (CCL4). The classifier also calculated signature scores for each sample which was significantly different between MGD-DE patients and controls (Mann-Whitney U, p ˂ 0.001. These 4 genes showed a high correlation with the clinical signs in our patients: OSDI, Schirmer test I, BUT, Osmolarity (Pearson correlation p<0.001) and very significant with the more specific signs of MGD, vascularization and lid margin thickness, p<0.0001, as well as the Meibomian glands, the operculum occlusion and gland dropout, p<0.0001.

1.- The Transcriptomic mRNA and multiplexed approach is an efficient method to analyze some of the most important changes that take place in patients with MGD and DED.2.- The genetic signature with only 4 genes represents an important advance to analyze the inflammatory response and help for the diagnosis and treatment strategies.3.- This genetic signature with 4 genes (IFITM1, HLA-A, CTSS, CCL4,) reduces the cost of the test significatively, which will allow it to be performed on most patients with MGD and ED.